Green Walls Research Articles

Optimum thermal performance of green walls systems and design requirements against heat transfer of conventional external walls of low-rise concrete buildings in hot regions

This paper presents a study on how the thermal performance of conventional external walls of concrete building could be improved against heat transfer in hot regions. 45 buildings were visited to observe the heat transfer from the warmer side of the external wall to the cooler side. The measurements showed that the conventional walls are insufficient because of high indoor temperatures. This study introduced three environmentally friendly scenarios to enhance the efficiency of the concrete wall against heat transfer. In the first scenario, a continuous air layer was added at the middle of the wall to form an aired-concrete wall. In the second scenario, a living green layer was added on the exterior side of the wall to form a living-concrete wall. The third scenario merged the previous two insights to form a living-aired-concrete wall. Thermal models were prepared to conduct thermal analysis. The results showed that the air layer deactivates the work of thermal bridges and improves the thermal resistance of the wall 5 to 15 times. In the aired-concrete wall, the results showed that the minimum depth of the air layer should be at least 6 cm, to secure a convenient indoor environment with indoor temperature not more than 25 °C. Furthermore, the results showed that adding only an outdoor living green layer to the conventional wall is insufficient in all thermal zones of hot regions. Finally, the best thermal performance against heat transfer was found in the living-aired-concrete wall using outdoor Perennials plants and 5 cm middle air layer.

Toxic metals from atmospheric particulate matter in food species of tomato (Solanum lycopersicum) and strawberry (Fragaria x ananassa) used in urban gardening. A closed chamber study

In this work, two plant foods, strawberry and tomato, were subjected to exposure to metals from synthetic airborne particles in a closed chamber experiment. The synthetic particles were obtained in the laboratory. Within the closed chamber, particles were added and recirculated for 4 days in a turbulent air stream, causing deposition on the different parts of the plants. They were evaluated because of their increasingly frequent cultivation in urban gardens of cities. The main objectives were to determine whether the species accumulate metals significantly, which species accumulate the most, and in which parts of the plant. Finally, an attempt was made to differentiate the accumulation of pollutants by surface deposition on leaves and fruits from the adsorbed metals into the leaf or the fruit by their stomata or cuticles. The concentration of heavy metals was quantified in fruits, leaves and the soil after exposure. Metals were evaluated as a whole and individually, both in dry and fresh weight basis. The decrease of particulate matter and metals in the air inside the chamber was also studied in order to evaluate the use of both food species as air purifier by vertical gardens. The concentration of metals in plants (mg kg−1) and airborne particles (mg m−3) was measured by microwave plasma optical emission spectroscopy (MP-AES). For the sake comparison of total amount of metals in the samples concentrations were normalized. Strawberries was the food species that accumulated the largest amount of metals. In a dry weight basis, tomato leaves and strawberry fruits were the parts of the plants with higher accumulation capacity of particles and metals. The potential toxic elements Cd, Ni and Cr in tomato leaves and in strawberry fruits had a higher presence in the interior of the plant system. In a fresh weight basis, the strawberry fruit had the most accumulation capacity for metals.

Vertical greening: The state of the art in digital modeling and simulation

The scientific literature on vertical gardens presents gaps in the systematization of botanical parameters related to modeling and simulation. To address these gaps, the article aimed to investigate and identify parameters and modeling processes necessary for configuring vertical greening systems in computer simulation software. The systematic literature review method was employed to gather all scientific publications from the past ten years. As a result, the article presents the processes for 3D modeling, the most common software, and information tables containing botanical parameters used for configuring vegetation. Additionally, the work provides an overview of studies conducted on this topic in Architecture in recent years, highlighting other gaps and shortcomings in knowledge for possible future research.

Evaluating the efficiency of a living wall facade as a sustainable energy-saving alternative in hot arid regions

Buildings can generate heat from a variety of sources, including building occupants, the sun, lighting and radiance, and cooling equipment, the energy consumed by which results in heat. Egypt is experiencing rapid economic growth, improvements in urban spaces, and a reduction in green space, all of which contribute to the occurrence of environmental problems such as pollutants, increased CO2 emissions, and increased energy consumption. Furthermore, the study focuses on the cases of architectural buildings that have been combined with living green facade as an innovative facade in order to address the energy crisis and climate change. The study on live greening techniques on building facades has raised a lot of interest. The primary purpose of this research is to utilize simulation software to manage the energy consumption usage of a green facade and compare energy demand levels to the basic scenario. Living green façades can offer zone-sensitive cooling on building facades, which is especially important during summer sessions in hot areas. Green facade cooling loads have an effect on interior air quality by keeping the façade from warming up. The research investigates the cooling impact of three types of living green walls in Egypt using Design-Builder simulation software. To estimate the energy consumption rates of the base case building, the Design-Builder simulation program was used in conjunction with the Energy Plus engine. According to the findings, the indirect green façade with planter boxes of green walls has reduced the high energy consumption compared to the buildings with direct and indirect green façade, increased thermal comfort, and reduced CO2 emissions. As a result of the estimation, it was determined that the energy demand standards of the living wall were lower than the energy demand standards of buildings without the living wall of the same measurement, saving 75% of the energy.

Experimental analysis to assess the hydrological efficiency and the nutrient leaching behavior of a new green wall system

Green Walls represent a sustainable solution to mitigate the effects due to climate change and urbanization. However, although they have been widely investigated in different fields of science, studies on the potential of these systems to manage urban stormwater are still few. Moreover, even if these systems provide multiple benefits, as other nature-based solutions, they leach nutrients due to growing media, decomposed vegetation, and the possibility of fertilizer use. In this regard, several studies have evaluated the nutrient concentrations in the runoff from green roofs, while studies that have analyzed the nutrient-leaching behavior of green walls are still limited. To bridge these scientific gaps, this study presents experimental findings on the hydrological efficiency and nutrient-leaching behavior of an innovative modular living wall system. Some rainfall-runoff tests were carried out to assess the hydrological response of a new green wall system in retaining stormwater. To evaluate the concentration of the nutrients, the collected outflow was analyzed by spectrophotometer UV–visible. The findings show that the developed green wall panel presents good retention capacity by considering different simulated rainfalls and varying the initial soil moisture conditions. The results in terms of nutrient concentrations highlight that the vegetation life cycle and the fertilizer uses affect the quality of the water released from the green wall panel. The concentration of the analyzed nutrients is influenced by the simulated rainfall's hydrological characteristics and the days between the planting phase and the test. However, the overall results show that the concentrations of each analyzed nutrient are low, except after the fertilizer use, highlighting that the choice of vegetation that does not need external nutrients should be preferred during the design of a green wall.

Phytoremediation of indoor air pollutants from construction and transport by a moveable active green wall system

No sustainable, economical and scalable systems are currently available for the direct removal of construction and transport related air pollutants from working environments in these locations. Active green walls have previously demonstrated the capacity to effectively filter NO2, O3, and PM2.5 from indoor and roadside air. This project assessed the air quality provided by a portable active green wall in a construction site office involved in a construction upgrade of train depot, and compared it to a matched reference office to ascertain the active green wall's potential to enhance air quality. Through comparisons between time-matched samples, we established differences in air quality between the ambient and filtered air streams, and thus calculated the single pass removal efficiency provided by the active green wall for each pollutant. A comparison between the two site offices demonstrated that the active green wall produced significant improvements on the air quality of this unique indoor environment, with reductions in PM2.5 and O3 detected, with the active green wall achieving single pass removal efficiencies of 56.42 ± 21.02% and 20.73 ± 0.87% PM2.5 and O3, respectively. The active green wall also caused a small increase in dew point, but had no effect on humidity and temperature, possibly due to the small scale of the system relative to the volume of the test structure. The findings suggest phytoremediation may be an effective method for removing construction and transport associated PM2.5 and O3. Conversely, future research is needed to investigate NO2 removal, with substrate developments potentially required to address this.

Performance of Ornamental Plants in Different Media Composition for Outdoor Vertical Gardening: Experimental Investigation

The present experiment was carried out during August 2022 to November 2022 in Research Field , Department of Horticulture SHUATS, Prayagraj. The experiment was conducted in Factorial Plot Design (FPD) with five media composition i.e (Soil, Perlite, Sand, Cocopeat,) in different proportion viz. M0-Soil,M1- Perlite +Cocopeat+Sand 1:1:1,M2- Perlite +Cocopeat+Sand 1:1:2,M3- Perlite+Cocopeat+Sand 1:2:1,M4- Perlite+Cocopeat+Sand 2:1:1 in plastic pot for outdoor vertical gardening. Total number of plants are 150, there are two factors .Five variety and each varieties have five plants with three replication. Second factor is the different types of plant such as Begonia semperflorens, Crassula ovata, Syngonium podophyllum, Coleus scutellarioide, Iresine herbstii. From the present experimental growth parameter and ornamental morphological characters observed. Among the five ornamentals plants used Coleus scutellarioide and Jade performed better as ornamentals plants used in vertical garden system with growing media and the media composition M4 (Perlite+Cocopeat+Sand 2:1:1) is the best media composition for the plant growth.

Benchmark of plant-based VOCs control effect for indoor air quality: Green wall case in smith campus at Harvard University

The emission of volatile organic compounds (VOCs) from interior materials can significantly impact people's health and daily activities, necessitating effective management. In the construction of the interior built environment, plants serve as a suitable means to enhance air quality. They not only function as ecological living materials for air purification and VOCs removal but are also valued for their aesthetic appeal. However, often the emphasis in designing green infrastructure is placed more on the aesthetics of planting design rather than considering plants' ecological properties. This research examines the ability of 12 plant species used in the interior green wall design at Harvard University's Smith Center as a case study to decompose and absorb VOCs through experimental studies. By integrating ecological properties and key factors such as spatial and budget constraints into the design process, this research explores the potential of using an algorithmic model to select plant species capable of reducing interior VOC pollution in green wall design. The significance of this study lies in its contribution to indoor environmental health and environmental management practices through providing a potential plant selection model and suggesting a relevant workflow for interior planting design with the goal of controlling VOC emissions. By leveraging the knowledge gained from experiments on the VOC removal abilities of selected plant species, this study offers a valuable resource for practitioners seeking to create innovative indoor air cleaning and decontamination technologies.

Abandon the idea of ‘great green walls’

Abandon the idea of ‘great green walls’

The cooling intensity of green infrastructure in local climate zones: A comparative study in China's cold region

We compared the effect of green cover on common urban green infrastructure (UGI, roof greening, vertical greening, and ground trees) to determine the relationship between the cooling efficiency and local climate zones (LCZs) in Xi'an, China using numerical simulations. We found that: 1) The temporal variation of pedestrian cooling intensity (PCI) among LCZs, varied; the maximum PCI of green roofs occurred at 11:00 in low-rise buildings and 13:00 in mid-rise and high-rise buildings. The maximum PCI of green walls occurred at 19:00. 2) The spatial pattern of PCI was dominated by the wind direction, with its maximum occurring downwind of the block. 3) The cooling intensity (CI) of green roofs and green walls was more greatly influenced by building geometry than green cover, with greater CI in compact blocks. This was the opposite for ground trees. 4) The maximum PCI per unit of green area occurred in open low-rise buildings with low-cover green roofs (0.30 °C/ha), compact low-rise with low-cover green walls (0.21 °C/ha), and compact mid-rise with high trees cover (0.56 °C/ha). Our results provide theoretical guidance for urban designers to implement UGI design by considering the spatial and temporal variation patterns of CI under different LCZs.

A study on evaporative cooling capacity of a novel green wall to control ventilating air temperature

Green buildings include structures that have passive indoor environmental control benefits, while green walls and roofs may offer extensive water holding capacity, reduced run out time, sound absorption, and fortified biodiversity in urban settings. Conventional green walls additionally provide passive cooling benefits via surface evaporation and plants' transpiration. In this study, a novel green wall comprised of bio-receptive porous concrete tiles was tested for its ability to act as an evaporative cooling pad. Ryegrass was grown on its surface, and air passed through the vegetated wall to determine its evaporative cooling effect. This novel green wall evaporative cooling pad (GWECP) showed a maximum cooling effectiveness of 0.97 with a maximum temperature reduction of −25.58 °C with 50 °C inlet air temperature. The effect of vegetation layer height was further examined, where a grass layer 30 cm in height showed a maximum cooling rate of −9.57 ± 0.79 kW, and a grass layer 22.5 cm in height showed a maximum evaporation rate of 3.36 ± 0.08 g s−1 when challenged with different inlet air conditions ranging from 25 °C to 50 °C. As a novel evaporative cooling system, the GWECP had maximum cooling and evaporation coefficients of 10.7 kW m−2 C−1 and 1.18 g s−1, respectively. This data set suggests a prospective application for this GWECP as an energy-efficient cooling system for ventilated air by providing carbon-free indoor air-cooling for any extremely warm outdoor weather conditions with the other associated benefits of green walls.

Treatment of Potted Zebra Plant and Inch Plant with Antigibberellin Plant Growth Regulators Slows Stem Elongation in an Interior Green Wall

In commercial interior green walls, plant trimming and replacement necessitated by stem elongation under low interior light levels is labor intensive and costly. Antigibberellin plant growth regulators (PGRs) may slow stem elongation and thus reduce maintenance costs in this environment. In Expt. 1, two PGRs were applied as foliar spray or drench to three spiderwort selections [two of zebra plant (Tradescantia zebrina) and one of inch plant (Tradescantia fluminensis)] immediately before installation in a green wall, each at three rates: ancymidol (ANC) foliar spray at 25, 100, and 200 mg·L−1; paclobutrazol (PBZ) foliar spray at 20, 80, and 160 mg·L−1; and PBZ drench at 1, 4, and 8 mg·L−1, along with an untreated control. In Expt. 2, 80 mg·L−1 PBZ foliar spray, 1 mg·L−1 PBZ applied via subirrigation four times, and the combination of these two treatments, was evaluated on ‘Burgundy’ zebra plant. In both experiments, plants were placed in a vertical modular tray interior green wall. Change in total stem and specific internode length were measured every 14 days after installation for 3 months to calculate growth per month. Antigibberellin application slowed internode elongation of spiderwort selections during the first month after installation. Antigibberellins were more effective in zebra plant at reducing overall stem growth rate and less so on inch plant. Across the three spiderwort selections, 25 mg·L−1 foliar spray of ANC resulted in no difference in growth rate when compared with the control, although 100 to 200 mg·L−1 foliar spray was effective. Based on the results of both experiments, moderate and high rates of PBZ, applied both as a foliar spray and drench, resulted in similar reduction in stem elongation. PBZ applied as 20 to 80 mg·L−1 foliar spray, 4 mg·L−1 drench before installation in the wall, or a combination of an 80 mg·L−1 PBZ pre-installation foliar spray and recurring 1 mg·L−1 via subirrigation (four times) were effective at growth suppression of spiderworts for at least 3 months. Even rates of PBZ of 160 mg·L−1 foliar spray or 8 mg·L−1 drench did not show phytotoxicity in treated plants and could be considered for use. We recommend a pre-installation application of 80 mg·L−1 foliar spray or 4 mg·L−1 drench for controlling stem growth across spiderwort selections. Application of antigibberellin PGRs to plants before installation in green walls slows stem growth and can contribute to reduced maintenance costs.

Monitoring and performance evaluation of a green wall in a semi-arid Mediterranean climate

Green walls are gaining popularity as a sustainable cladding solution for buildings, offering various advantages for the built environment and human well-being. However, there is a lack of research on plant selection guides and field data in semi-arid Mediterranean climates, limiting our understanding of green wall potential. To address these gaps, this study assesses the hygrothermal and sound insulation performance of a modular living wall in a semi-arid Mediterranean climate and develops a plant-selection guideline for green wall applications. The experiment involves a comparative assessment between the modular living wall and a bare-wall-reference facade. Measurements of air temperature, relative humidity, and sound pressure were taken, along with thermal imaging, to record the surface temperatures of the experimental facades. Results reveal that the modular-living wall significantly decreased dry-bulb air temperature (up to 8 °C) and reduced sound pressure by up to 5.1 dB. Additionally, relative humidity in the air cavity behind the modular living wall consistently increased by 6.6%, with a maximum absolute humidity differential of 8.6 g/kg. Thermal imaging showed a surface temperature difference of up to 27 °C, with foliage having a higher leaf-area-index proving more efficient in reducing the surface temperature of the green wall.Overall, the modular living wall effectively protected building walls from high solar radiation and temperatures, resulting in reduced energy requirements for space cooling. However, proper irrigation and plant health maintenance are necessary. This study fills important research gaps, providing valuable insights into the potential benefits and performance of green walls in semi-arid Mediterranean climates.

Improving Urban Habitat Connectivity for Native Birds: Using Least-Cost Path Analyses to Design Urban Green Infrastructure Networks

Habitat loss and fragmentation are primary threats to biodiversity in urban areas. Least-cost path analyses are commonly used in ecology to identify and protect wildlife corridors and stepping-stone habitats that minimise the difficulty and risk for species dispersing across human-modified landscapes. However, they are rarely considered or used in the design of urban green infrastructure networks, particularly those that include building-integrated vegetation, such as green walls and green roofs. This study uses Linkage Mapper, an ArcGIS toolbox, to identify the least-cost paths for four native keystone birds (kererū, tūī, korimako, and hihi) in Wellington, New Zealand, to design a network of green roof corridors that ease native bird dispersal. The results identified 27 least-cost paths across the central city that connect existing native forest habitats. Creating 0.7 km2 of green roof corridors along these least-cost paths reduced cost-weighted distances by 8.5–9.3% for the kererū, tūī, and korimako, but there was only a 4.3% reduction for the hihi (a small forest bird). In urban areas with little ground-level space for green infrastructure, this study demonstrates how least-cost path analyses can inform the design of building-integrated vegetation networks and quantify their impacts on corridor quality for target species in cities.

Use of Cactus and Succulents in Vertical Gardens

A vertical garden is a type of garden created by arranging plants on a vertical surface. It is often used for growing plants on vertical surfaces such as walls, fences, buildings, balconies and terraces in cities with limited garden space. The plants are planted in custom made vertical garden panels or containers and the roots of the plants are placed in a special soil mix in the panel. Special systems can be placed behind the panels for irrigation and fertilization. Vertical gardens provide a suitable environment for many plant species. In such gardens, flowers, herbs, shrubs, vegetables and even trees can be grown. In this paper, cactus and succulents that can be used in vertical gardens will be evaluated.

A Novel Strategy for Converting Conventional Structures into Net-Zero-Energy Buildings without Destruction

The majority of energy consumption is attributed to buildings. Buildings designed with environmentally sustainable features have the potential to reduce energy consumption. The demolition of ecologically detrimental structures incurs expenses and damages the natural environment. The act of constructing models for the purpose of destruction was deemed superfluous. The replication of the structural model was accompanied by a modification of the design, and a variety of tactics were employed. The proposed upgrades for the building include the installation of new windows, incorporation of greenery on the walls and roof, implementation of insulation, and integration of solar panels in a four-story residential building in Najran, Saudi Arabia. Simultaneously installing insulation prior to changing windows will ensure that the energy consumption of the building, green wall, or green roof will remain unaffected. The installation of solar panels on the walls and top roof of a structure has the potential to generate a monthly electricity output up to two times greater than the structure’s consumption. The spas can be heated on a daily basis by substituting the heating system with solar collectors. The implementation of sustainable building practices has resulted in a significant reduction in energy consumption. Specifically, electricity, gas, heating, and cooling consumption decreased by 11%, 85%, 28%, and 83%, respectively.

Studi Pendekatan Biofilik pada Rumah Sakit Tipe C di Area Relokasi Erupsi Semeru Kabupaten Lumajang

Lumajang city has six hospitals that can be used by the people, but has a very far distance from residential areas around Mount Semeru, especially in the relocation area for survivors of the Mount Semeru eruption. The design of a type C hospital in the relocation area of Mount Semeru eruption survivors is a manifestation of disaster risk management through programs and policies to minimize the impact of disasters. The method of discussion is a descriptive qualitative with the literature studies as the main sources. The design process used leads to a repeated continuously process. Design using biophilic architecture is a design that provides an opportunity for people to live in a healthy environment, a place that can reduce stress by integrating natural elements into the design. This is according to the patient’s condition who requires elements of environment that can accelerate recovery. Biophilic architectural approaches that can support the patient's healing process, such as providing a garden as the main orientation, green walls, skylight, and static rooms with balconies come with colorful plants such as bougenville, rose, and hibiscus that are pleasing to the eye.

Формирование микроклиматических условий с помощью вертикального озеленения

The article provides data on the study of the influence of vertical landscaping on the microclimatic conditions of urbolandschafts in the eastern part of the Rostov region. Maximum environmental protection functions in plants are noted during the period of active growing. The most common species in vertical landscaping of the steppe zone is Parthenocissus guinguefolia L. The change in illumination behind the "green wall" of girls' five-source grapes occurs from 20 to 71.1% compared to control, where there is no vertical landscaping. The growth of Parthenocissus guinguefolia L. allows you to reduce the temperature near the facade of the building on the south side by 4.7 ° C and on the north side by 3.1 ° C. The studies made it possible to identify a pattern of noise reduction due to the density of the surface coating with lyana. The greatest insulation of air noise is noted at metering sites, where the coating density is more than 75%. Along the roads, the leaves of Parthenocissus guinguefolia L. are able to deposit up to 5 g/m2, and in the living area up to 2 g/m2 of dust, thanks to the architectonics of the sheet plate. The correct selection of species, placement, as well as the use of measures regulating the growth and development of vines will create favorable microclimatic conditions for urbanized territories. Keywords: VERTICAL LANDSCAPING, GIRLS 'GRAPES, FIVE-MAINS, LIANS, NOISE INSULATION, SORPTION CAPACITY, TOLERANCE

Aeolian disaster risk evaluation in the African Sahel

The Sahel is facing a serious environmental crisis due to aeolian disaster that has seriously affected the local development and survival of residents. Thus, evaluating the aeolian disaster risk levels and their variation in the Sahel is important. This study established an optimal model by evaluating the applicability of different models in the aeolian disaster risk determination in the Sahel. Using this model, the spatiotemporal changes in the risk subsystem of aeolian disaster (hazard, sensitivity, vulnerability, and restorability) and the aeolian disaster risk in the Sahel from 2000 to 2020 were analyzed. Based on this analysis, the impact of climate change and human activities on the aeolian disaster risk in the Sahel was evaluated. Results revealed that the variable fuzzy recognition (VFR) based on the aeolian disaster risk index (ADRI) model had the highest accuracy, reaching 89.72 %. The middle of the Sahel, located in the desert-grassland transition zone, exhibited a high hazard, sensitivity, and vulnerability, rendering it highly susceptible to aeolian disaster. The proportion of areas with very low and very high aeolian disaster risk levels decreased from 2000 to 2020, while those with low and high levels increased, and the change in moderate risk level areas remained relatively stable. Areas of low, moderate, and high risk are more sensitive to climate change and human activities and are subjected to greater pressure for change. Human activities were the main factor for the change of ADRI in the Sahel, accounting for 69.74 and 58.19 % of the increased and decreased areas of ADRI, respectively. This study evaluated the level of aeolian disaster risk in the Sahel and identified the main driving factors, providing a reference for Sahel countries to better implement the Green Great Wall (GGW) program in Africa, thereby mitigating the adverse effects of aeolian disaster.

Sustainable Mitigation Strategies for Urban Heat Island Effects in Urban Areas

The globe is at a crossroads in terms of the urban heat island effect, with rising surface temperatures due to urbanization and an expanding built environment. This cause-and-effect connection may be linked to weather-related dangers, natural disasters, and disease outbreaks. Urbanization and industrialization will not lead to a secure and sustainable future. Finding solutions to problems such as the heat island effect is at the forefront of scientific research and policy development. Sustainable ways to decrease urban heat island impacts are a core principle for urban planners. This literature study examines the benefits of adding green infrastructure and sustainable materials in built-up areas to reduce the urban heat island effect. Materials such as reflective street pavements, coating materials including light-colored paint, phase-change materials, color-changing paint, fluorescence paint, and energy-efficient appliances are considered sustainable materials, whereas green infrastructure like green roofs, green walls, green parking and pavements, and shaded streets are considered to mitigate the urban heat island effect. The hurdles to the widespread adoption of such practices include a lack of governmental legislation, insufficient technological development, an erroneous estimation of economic gains, and unwillingness on the part of impacted parties.