Vertical Greenery Research Articles

Meadow-living walls: Creating attractive vertical greenery with meadow seed mixtures – Experiences and recommendations from a three year field trial

Living walls (LW) are a way to increase urban green infrastructure. Previous research has mainly focused on microclimatic cooling effect or the technical functioning of LW, while the development of autochthonous plant species and visual plant aspects for LWs have largely been neglected. In this study we focused on the possibility of establishing LWs by seeding, which is not used very often despite obvious advantages such as low costs, low maintenance requirements, and a high species diversity potential.Within a three-year field study in a temperate oceanic climate, we established a meadow-LW by sowing seed mixtures of >30 species on textile mats without soil substrate. After a pre-growing period with horizontal mats in the greenhouse, we placed the greened mats vertically on experimental walls exposed to the North, South, East, and West. We documented species coverage and visibility over time, growth height, and maintenance steps. After cutting, the vegetation recovered within a few weeks and we recommend one complete cut in summer and removing dead plant material after the frost period.From April to October, we observed an increasing growth height and vegetation coverage reaching >100%, followed by a decline till December. Differences of plant species composition and development between different expositions and study years were observed especially after the cold winter of 2017/2018.This study was able to demonstrate that seeded meadow-LWs can be easily established. The use of autochthonous plant species mixtures can create new biodiverse habitats, are aesthetically attractive and increase human wellbeing.

Narrative Review Approach on the Readiness of the Vertical Greenery Adaptation to the Public-School Building in Malaysia

Global climate concerns include deforestation and environmental change. The implementation of the concept of reintroducing nature to the urban school landscape may promote sustainable development and enhance the city’s environment quality. The Vertical Greenery System (VGS) is an important aspect in public school building because it offers sustainable urban schooling the benefits. However, low awareness school amongst government and public, as well as concerning on additional cost of construction and maintenance have become a barrier in adopting the VGS in public-school. Due to lack of studies and analysis on VGS implementation in schools, this paper aims to examine the VGS adaptation strategies towards the readiness of VGS implementation in public school buildings as well as the implications for students’ social well-being. This paper focuses on using a narrative review method and deductive thematic analysis to perceive the readiness of VGS adaptation amongst government and public in public school building. The projected outcome will explore the cost-benefits of VGS installation, with considerations of environment, and social well-being towards public-school. Hence, this paper also suggested that VGS can significantly improve the student learning performance, social interaction amongst student’s experience and overall built environment of public-school.

Effects of microclimatic factors on stomatal conductance of plants in vertical greenery systems in humid subtropical areas

• Reduced irrigation in winter does not significantly affect VGS. • The transpiration in winter is about 1/3 of that in other seasons. • The E of southwest-oriented VGS is 41% higher in the afternoon than morning. • A stomatal model in VGS in humid subtropical areas is proposed. Plant transpiration through stomata is crucial in land surface physical processes and the hydrosphere-atmosphere-biosphere water vapor cycle. Applying stomatal models to vertical greenery systems (VGSs) is challenging because of the unique plant habitat. However, VGSs are widely used in subtropical areas; thus, plant transpiration in these systems should be investigated. Field measurements are used to determine the relationship between stomatal conductance ( g s ) and different microclimatic factors: solar radiation ( I ), air temperature ( T a ), relative humidity (RH), and soil volumetric water content ( θ ). A stomatal model based on multiple nonlinear regression is proposed, and its accuracy for different VGS plant species is verified with field measurements. The model's root mean square error (RMSE) is 57% lower than that of existing models. The latent heat flux from transpiration ( E ) of VGS in different seasons and orientations are calculated, and design strategies are proposed to utilize the cooling potential of VGS better. The prediction accuracy of the water vapor transfer, thermal comfort, and building energy consumption can be improved by incorporating the proposed model into an urban canopy model (UCM) and building energy model (BEM). It will provide guidelines for sustainable urban planning and VGS design regarding heat island mitigation and building energy savings.

Plant growth-promoting microbes improve stormwater retention of a newly-built vertical greenery system

On-site decentralized urban stormwater management has gained significant momentum in urban planning. Recently, vegetated roofs have been recommended as a viable decentralized stormwater management system and nature-based solution to meet the challenge of urban floods. However, as another type of unconventional green infrastructure, vertical greenery systems (VGS), also known as vegetated facades, have received much less research attention. Even though some researchers suggest that stormwater management by VGS is comparable to that of vegetated roofs, empirical evidence to substantiate this claim is limited. In this study, we conducted rain simulations on newly-built vegetation containers with water storage compartments. These vegetation containers were designed to be incorporated into a VGS specifically for stormwater management. We tested variables that could influence water retention efficiency and evapotranspiration of the containers under field conditions, i.e., inoculation of plant growth-promoting microbes (PGPMs) (Rhizophagus irregularis and Bacillus amyloliquefaciens), different substrate types (sandy loam and reed-based substrate), simulated rain quantity, natural precipitation, substrate moisture, and air temperature. The inoculation of PGPMs significantly reduced runoff quantity from the vegetation containers. Meanwhile, the well-ventilated sandy-loam substrate significantly reduced the remaining water in the water storage compartments over 1-week periods between rain simulation events, achieving high water-use efficiency. The selected microbes were established successfully in the containers and promoted the growth of 2 out of 5 plant species. R. irregularis colonization responded to substrate type and host plant species, while B. amyloliquefaciens population density in the substrate did not respond to these factors. Environmental conditions, such as antecedent substrate moisture, air temperature, and natural precipitation also influenced the efficiency of stormwater retention and/or evapotranspiration. In conclusion, this study provides instructive and practical insights to reduce urban flood risk by using VGS.

Green-blue infrastructure in the built environment – sustainable and resource-saving designs for urban structures and open spaces

Urban grey infrastructure, as it generally consists of monofunctional, sealed, impervious, heating up and reflecting surfaces, has led to a series of serious challenges (urban heat stresses, loss of biodiversity, flood risks and natural hazards) decreasing urban resilience. Ongoing construction activities result in irreversible soil consumption and loss of its numerous and vital functions. However, a common understanding has been evolving that the establishment of green-blue infrastructure (GBI) supports compensating for functional losses, as they are integrative and provide pervious, absorbent, shading and non-heating up surfaces. We present a concept to holistically interconnect stand-alone approaches to improve and support constructional design for transforming green open spaces addressing specifically urban landscape construction and building greenery. The underlying state of knowledge emerges from currently four ongoing projects on advancing GBI for re-establishing ecosystem functions and diverse habitats: 1. The Circular Soil Concept targets the reuse of excavated soil materials from construction sites to produce engineered soils. These are applied as functional vegetation substrates for landscape construction and installing building greenery, saving scarce soil resources while generating large scale and vegetated areas with climate change adaptation performance. 2. The StreetTREE-Planter is designed to install urban trees in a given street infrastructure. The advanced planter systems will support extended tree lifespans, microclimatic benefits, flood protection and urban resilience. The design is based on targeted rainwater harvesting for irrigation management in alignment with water requirements and the desired microclimatic performance. 3. The GLASGrün projects generates plant-based shading designs for glass facades. As plants and their leaves do not heat up from solar radiation, vertical greenery is promising, however challenging, for green shading of glazed surfaces and for indoor and outdoor microclimatic regulation. 4. The INReS rainwater management tool was developed as a prototype web application to integrate sustainable, plant-based rainwater management systems into BIM-(Building Information Modeling)-based construction projects. It provides up-to-date design for the wider public and specific planning guidelines. In synthesis with the present and upcoming findings of these projects, a parameter-based and BIM-compatible GBI-design management tool is foreseen to better and sustainably integrate GBI systems into construction projects, and to consider the resource question.

Sustav vertikalnog ozelenjavanja - model za poboljšanje energetske učinkovitosti zgrada

Adaptation to climate change in cities is essential, and vertical greenery systems (VGSs) are used as a means of restoring the urban areas’ ecological integrity. This paper presents the classification, typology, and benefits of the VGS for the energy performance of buildings. To analyse its energy and environmental impacts, the use of VGS was simulated on the façades of residential buildings in the urban area of the City of Banja Luka. The results showed that VGS reduced the temperature of the wall and air in and around the buildings, as well as the emission of CO2 in the air.

Study on the Relationship between Restoration Benefit and Visual Satisfaction of LONG-PLAN’s Indoor Vertical Greenery

This study investigates the psychological restorative benefits of indoor vertical greenery and its relationship with visual satisfaction. Taking the Solar Decathlon China 2018 champion project “LONG-PLAN” as the experimental field, we conducted a questionnaire survey to evaluate the effect of indoor vertical greenery on creating a restorative environment. Then we further studied the relationship between the restorative environmental factors and visual satisfaction of indoor vertical greenery. The results show that: (1) Indoor vertical greenery has a positive impact on the subjective restoration of respondents (the average value of PRS = 4.150). (2) The three factors of “being away,” “fascination and compatibility,” and the “extent” of environmental restoration have a significant positive correlation with the visual satisfaction of indoor vertical greenery (the correlation coefficient values are 0.403, 0.627, and 0.425, respectively, p < 0.01). (3) In the stepwise regression analysis of the three factors and the visual satisfaction of indoor vertical greenery, only “fascination and compatibility” show a significant positive correlation (the regression coefficient = 0.753, p < 0.01). (4) The visual satisfaction of indoor vertical greenery has a significantly positive impact on environmental recovery (the regression coefficient = 0.459, p < 0.01). The study shows that indoor vertical greenery improves visual satisfaction and contributes to a restorative environment. In addition, the study provides further evidence of the mutual facilitation between restorative benefits and visual satisfaction.

Sky Gardens, Public Spaces and Urban Sustainability in Dense Cities: Shenzhen, Hong Kong and Singapore

This paper studies the spatial characteristics of sky gardens as public spaces to explore their potential to support urban sustainability in dense cities. This research understands public spaces as spaces that are open and available in different levels of access and use. The research focuses on 982 sky gardens in Shenzhen, Hong Kong, and Singapore. It adopts a mixed methodology, including site visits and observations, statistic measurements (based on SPSS software), and Grey Relation Analysis (GRA) methods. The research follows three steps: first, it studies the urban context, including urban density, land uses, and policy regulations regarding sky gardens and sustainability. Second, it examines sky gardens’ spatial characteristics in terms of form (morphology, typology, size, affordances, configuration), openness quality (accessibility, ownership, permeability), and geometry (open space ratio, height of space-to-building, void-to-solid ratio, shape index). Third, the research compares the findings in three case cities and discusses their potential to support urban sustainability. The results suggest that despite the limitations of sky gardens, they may play, to different degrees, fundamental roles as open public spaces in high-density urban environments supporting cities’ sustainability. High-density environments offer more opportunities for the sustainable development of sky gardens, which creates a new spatial paradigm for compact vertical greenery in high-density cities.

IMPLEMENTING VERTICAL GREENERY ON OFFICE FAÇADE OPENING TO IMPROVE INDOOR LIGHT QUALITY

In medium-rise office building on tropical climate, façade fenestration mostly dominated by glass curtain wall. In this case, an effort should be done to control the daylight penetration and to shade glare of low sun angle especially from west orientation. The idea is utilized the vertical greenery system (VGS) on facade opening, how it performs as glare limitation as well as accommodating view. Firstly, the variable of artificial shading to light parameter are studied. Then, the previous research of VGS were explored, to find its influential variables. The last step was developed recommendation of VGS implementation on office facade opening to improve light quality. Finding from the study, the most influential variables are the plant species suitable to the climate condition, its canopy leaves area as light variable, and the placement; an integration the plants construction system with other facade elements which consider light angles of incidence and viewer’s sightlines.

Property managers’ awareness of the potential benefits of vertical greenery systems on buildings

Many human activities are carried out in buildings, suggesting that the contribution of buildings to global warming is significant. This study examines the awareness of property managers (estate surveyors and valuers) about the potential benefits of vertical greenery systems (VGSs) on buildings. The questionnaire for the study was administered online to property managers working with registered estate surveying and valuation firms operating in Lagos. On firm basis, a total of 282 property managers working for the firms were considered. Of this total, 127 responded to the questionnaire, but 121 (representing 42.9%) were of use in the analysis of data. The data were analyzed using the fuzzy synthetic evaluation method. The result showed that property managers were generally less aware, with an overall awareness level of 2.60. Further analysis showed that the property managers were less aware of the benefits of VGSs on buildings. The levels of awareness of the property managers about VGSs' environmental benefits, social benefits, and economic benefits are 2.65, 2.58, and 2.53 respectively. We conclude that an improvement in the level of awareness of the property managers would assist in the formulation of policies by the government towards the achievement of SDGs.

Vertical Greenery as Natural Tool for Improving Energy Efficiency of Buildings

The European Construction Sector Observatory outlined that green building envelopes as green roofs and walls contribute to the reduction of energy demand and CO2 emissions due to the air conditioning in summer periods, and the mitigation of heat islands in urban areas. For this reason, the understanding about the contribution of urban greening infrastructures on buildings to sustainable energy use for air conditioning is urgent. This paper focuses on the analysis of a vertical surface provided with a Parthenocissus quinquefolia (L.) Planch., a winter deciduous species, as green cover of a building, assessing the reduction of the solar radiation energy absorbed by the façade and, consequently, the heat flux (HF) transmitted into the internal ambient. This research shows that, in July, surface temperatures (STs) on the vegetated façade were up to 13 °C lower than on the unvegetated (bare) façade. Under the climate and environmental conditions of the green wall located at ENEA Casaccia Research Center, a saving of 2.22 and 1.94 kWhe/m2, respectively in 2019 and 2020, for the summer cooling electricity load, was achieved. These energy reductions also allowed the saving of 985 and 862 g CO2/m2 emissions, respectively, in 2019 and 2020. Ultimately, a green factor named Kv* was also elaborated to evaluate the influence of vegetation on the STs as well as on HFs transmitted into the indoor ambient and adapted to the case of a detached vertical green cover. Measurements of Kv* factor lasting three years showed the suitability of this index for defining the shading capacity of the vegetation on the building façade surfaces, which can be used to predict thermal gains and effects in a building endowed of a vertical green system.

Effects of different vertical façade greenery systems on pedestrian thermal comfort in deep street canyons

Vertical greenery systems (VGSs) have been adopted in city planning operations to mitigate excess heat in hot and humid subtropical cities. This study focused on the influence of different arrangements of vertical greening on pedestrian thermal comfort and particulate matter with a diameter of 10 µm (PM10) in street canyons. In this paper, the ENVI-met computational fluid dynamics (CFD) method was used to investigate the effects of different façade greenery arrangements with the same amount of greenery in the Nan Hai Yi Ku (NHYK) industrial district. On-site measurements were used to validate the simulation results in a transition season. The results showed that greening façades could improve pedestrians' thermal comfort with physiological equivalent temperature (PET) value reductions varying from 0.17 °C to 1.4 °C. Under a certain amount of greenery, the critical factor determining pedestrians' thermal comfort was the coverage rate of the greening façade near the pedestrian level. Specifically, increasing the greening façade coverage near the lower parts of street canyons could enhance the pedestrian-level cooling effect. In addition, the VGSs positively affected the pedestrian-level air quality in the street canyons. Nevertheless, the changes in pedestrian-level PM10 concentration induced by the presence of VGSs were not very obvious under the building-parallel wind direction.

Use of spicy aromatic plants in vertical greening

The article presents the advantages of vertical greenery to create urban development and improve the ecological condition of urban areas. The possibility of using spicy-aromatic crops in vertical greenery, which is an effective way of urban farming. The classification of vertical landscaping by types of plant placement is given and it is determined that modular phytowalls are the most suitable type of vertical plant placement according to the morphological features of spicy-aromatic plants. It is noted that additional research is needed on the possibility of growing perennial aromatic plants in light and relatively inexpensive hydroponic panels — Vertical garden system technology, developed by French designer Patrick Blanc. The technology of creation and functioning of spicy-aromatic phytowalls with the help of container and modular systems of vertical landscaping such as Cascade Wall and Pixel Garden PG14 is described. Attention is focused on the importance of the correct selection of the species composition of aromatic plants to create vertical compositions. The morphological and ecological features of the most common spicy-aromatic plants of the Lamiaceae family are characterized, which are the key parameters that determine the suitability of the described plants for use in vertical greenery. To create phytowalls outside and indoors, it is recommended to use rosemary (Rosmarinus officinalis L.), plants of the genus Thymus, Salvia, Mentha, as well as Cymbopogon citratus family Poaceae, Levisticum officinale Koch family Apiaceae and others. Attention is paid to mineral nutrition and protection of spicy-aromatic plants in closed soil conditions. Improvement of vertical landscaping systems and simultaneous search for adaptation of spicy-aromatic plants to the conditions of modular cultivation are relevant research topics for the further spread of this type of landscaping in temperate climates.

Evaluation of the critical parameters on the removal efficiency of a botanical biofilter system

Volatile organic compounds (VOCs) have increased public concern in terms of their adverse effects on health. Amongst VOCs, formaldehyde is significantly found indoors which can cause lung, leukemia, and nasopharyngeal cancers. Therefore, the requirement to find a suitable method and diminish the energy consumption of buildings has increased. Recent progress in vertical greenery systems has led to active systems known as active botanical biofilters. The current research represents an assessment of several essential parameters, based on the full-factorial model, for determining the functionality of a modular botanical biofilter and evaluating the role of plants and substrate to remove formaldehyde from the gas stream. Our findings showed that the maximum formaldehyde single-pass removal efficiency (SPRE) of 99.99% occurred at the lowest air flow rate (0.8 L/s) and concentration (0.3 mg/m3) through the 0.25 m2 filter, with any increases in air flow rate, met with a reduction in efficiency. At the same time, the utmost Clean Air Delivery Rate (CADR) of 17.46 m3/h was achieved at 5.5 L/s and 0.3 mg/m3. However, the system met the maximum Elimination Capacity (EC) of 30.64 mg/h at the highest inlet airflow (5.5 L/s) and pollutant concentration (2.06 mg/m3). Despite the role of biofilter segment to remove formaldehyde, the botanical components were found to be responsible for the system's SPRE of 13.51–28.07%, CADR of 0.39–5.46 m3/h, and EC of 0.12–11.45 mg/h. If the system is to meet current air standards, further development is required to increase its elimination capacity.

Stormwater Retention and Water-Use Efficiency of a Newly-Built Vertical Greenery System Suggests Effective Reduction of Urban Flood Risk

Stormwater Retention and Water-Use Efficiency of a Newly-Built Vertical Greenery System Suggests Effective Reduction of Urban Flood Risk

Vertical Greenery Systems: a comprehensive review

Due to the growth of modern cities, especially in metropolitan regions, the urban heat island has become a significant issue. In an effort to increase urban greenery and provide passive cooling, architects, engineers, building planners, and academics are turning their focus to vertical greenery systems (VGS). Greening the building envelope is not merely a matter of covering the outside of the structure with greenery. Green roofs and walls are often used as decorative elements in buildings. Green infrastructure research and development is growing gradually, deciding aesthetic enhancements as well as environmental, social, and economic advantages. Features like energy conservation, thermal insulation, environmental quality, health, and evapotranspiration underline the critical function of the vertical greenery system. However, these technologies may optimise the functional advantages of plants towards the performance of buildings and contribute to a sustainable urban rehabilitation and retrofitting strategy. Green wall systems design has been a major emphasis in recent years to obtain more efficient technological solutions and better performance throughout the construction process. In addition to lowering temperatures, vertical greenery systems provide other economic, environmental, and social advantages. According to the findings of the literature review, green roofs and facades are essential tools for reducing energy usage and greenhouse gas emissions.

Assessment of the Thermal Performance of Vertical Green Walls Using Overall Thermal Transfer Value Based BIM Simulation Method: Case Study of Residential Buildings in Sub-Tropics

Construction of multifunctional building envelopes using vertical greenery walls (VGW) has emerged as a sustainable green technology to improving cooling efficiency. To attaining the desired level of building cooling performance, VGW and overall thermal transfer value (OTTV) of the walls are useful design factors. The study aims to revise the current VGW evaluation, considering the decreased heat flux due to thermal efficiency of wall construction based on OTTV values. To achieve this, OTTV based Building Information Modelling (BIM) simulation method was proposed using Autodesk-Revit and DesignBuilder simulation based on EnergyPlus. Six wall compositions with various OTTV values of south facade for residential buildings located in sub-tropical in cooling season, were evaluated. The findings demonstrate that in the presence of a green system, a good OTTV value of the exterior walls is required for optimal performance, to keep the space within set point of cooling for long time during the cooling season. The comparisons between the bare walls and the VGW have demonstrated a great variation due to the different OTTV reached up to 6.57% and 18.44% reduction in indoor air temperature. The best combination of VGW resulted a maximum of 1.2°C reduction in indoor air temperature, with number of hours (within 28°C or less) were higher by 2506h, representing 85.59% of the overall number of hours (2928h). Overall cooling energy saving is found as 103.3kwh, representing 13.63% of the total of energy saving, and decreased the heat gained by 38.82%, representing 61.51kwh reduction during cooling season compared to base wall.

BIM-based LCA as a comprehensive method for the refurbishment of existing dwellings considering environmental compatibility, energy efficiency, and profitability: A case study in China

In the light of special attention of world governments to a viable and sustainable decarbonization way of the existing building stock, this article considered the feasibility of using a method of Building Information Modeling (BIM)-enabled Life Cycle Assessment (LCA) for the refurbishment in terms of environmental compatibility, energy efficiency, and profitability. An existing residential building in Nanjing was chosen as a case study. The paper investigated the environmental, energy, and economic efficiency of the case building hypothetically refurbished to the Passive House (PH) and “low energy building” (LEB) technologies. The analysis was made based on real construction and energy consumption data, monitored over three years. Also, a comparison of the environmental, energy-efficient, and economic feasibility of two hypothetical models refurbished to the PH and LEB technologies is considered. The results show that BIM-enabled LCA is a powerful tool for refurbishing existing residential buildings due to a comprehensive assessment of environmental compatibility, energy efficiency, and profitability. According to the results, special attention should be paid to reducing cooling loads, using materials with a high recycling rate and low cost, reducing the thickness of the insulation layer, using polyvinyl chloride (PVC) windows with movable sunshades, and setting horizontal and vertical greenery systems.

Thermal insulation effect of green façades based on calculation of heat transfer and long wave infrared radiative exchange

Vertical greenery systems offer an alternative method to reduce heat transfer through building envelope. This study conducted three experiments of green façades with different leaf coverage areas i.e. Bare Wall (BW) model, 50% leaf coverage area (GF-50%), and 90% leaf coverage area (GF-90%) to investigate its effect to overall heat transfer, radiative heat transfer, and Long Wave Infrared Radiative (LWIR) exchange on the wall. Calculation on the average of overall heat transfer showed BW model gained 2.10 W/m2 heat from outdoor environment. While GF-50% and GF-90% received 1.81 W/m2 and 1.46 W/m2, respectively. The contribution of leaf coverage area indicated BW absorbed 4% and 7% radiation heat transfer higher than GF-50% and GF-90%, respectively. The LWIR exchange of GF-90% was 6.76 W/m2 and 10.18 W/m2 lower than other. The findings lead to conclusion that increasing leaf coverage area of green façade can improve thermal insulation capacity of building wall.

Comparison of Shibataea kumasasa and Equisetum hyemale as vertical greenery system for thermal and light shade in student’s architectural design studio in Surabaya

Vertical greenery system (VGS) is commonly used for facade shading. It has many advantages in its natural aesthetic, air filter, carbon sequestration, and many more. This research is the continuation of the previous research in 2019, which used Shibataea kumasasa as VGS. It was found that using Shibataea as VGS has reduced the indoor air temperature by 0.5-2°C on average, with 5°C maximum temperature difference. On the other hand, it decreased more light (in range 26-95%), made the illuminance of the room lower than the standard requirement. A studio room should have minimum 5% daylight factor or 500 lux, while on the room measurement, the lowest was 20 lux in the morning hours, the highest was only 200 lux in the afternoon. As an attempt to look for vegetation with better performance, this research uses another bamboo species, Equisetum hyemale to be examined and then being compared to Shibataea. The result is that for the thermal shade, Equisetum performs less effectively than Shibataea. As for light shade, the Shibataea reduces more illuminance than Equisetum, thus makes it a less favorable alternative. The balance of thermal-light effective performance maintained by the leaf area index can be the focus of future research.