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Abstract Traffic-generated particulate matter (PM) pollution is a serious threat to human health and the environment, especially in urban settings. Recent studies have revealed the effectiveness of living walls in the reduction of this pollution; these systems use variable planting designs and their topographical dynamics might have an impact on PM dry deposition. This present study, employing an experimentally manipulable living wall system using box (Buxus sempervirens L.) plants, examined whether plants arranged in a design with heterogeneous topography have a differential PM removal capacity compared to plants in a design with homogenous topography. Two planting designs using 'short' and 'tall' plants, were simultaneously used on this living wall and equally exposed to traffic-based PM for 5 consecutive days. PM accumulation on leaves was estimated using an Environmental Scanning Electron Microscope and ImageJ image analysis software. The experiment was replicated four times changing the position of each design on the wall, and any variation in PM capture levels on leaves belonging to different designs were identified using a Generalised Linear Mixed-effect Models (GLMM). The planting design with topographical heterogeneity resulted in significantly higher PM densities (PM 10, PM 2.5 and PM 1) on leaf surfaces compared to a design with homogenous topography, indicating that topographical heterogeneity has a strong positive impact on the ability of plants to immobilise PM. Graphical abstract Unlabelled Image Highlights • Planting design of a living wall has an important influence on PM immobilisation. • Topographical heterogeneity of a planting design improves the leaf PM accumulation. • Interspersing species or using the same species with variable morphology improves PM deposition. [ABSTRACT FROM AUTHOR]

Abstract Expansion of modern cities reduces green areas, especially within city centres where the urban heat island has become a significant problem. In an attempt to increase greenery in cityscapes and to provide passive cooling, vertical greenery systems (VGS), an old practice of covering building façades with plants, are receiving attention from architects, engineers, building planners and researchers. This paper systematically reviews available publications on VGS and classifies them according to 13 distinct themes. Research into VGS has increased over recent years and the trend shows the approach to this field of research is changing. Thermal research remains the most prevalent theme compared to others, representing almost half of all publications (76 out of 166), with the top three most highly-cited articles all related to thermal properties of VGS. Nevertheless, the systematic review shows a strong trend of diversification into cross-disciplinary research. The proportion of VGS papers reporting on two or more themes has grown from 25% in 2011 to more than 60% in 2017. The review has revealed that among the limiting factors to VGS are cost and maintenance. The outcomes of this systematic review allow recommendations to be made to architects, designers, planners and owners of VGS regarding the need to account for maintenance in the overall design and operation of these systems. On the basis of this review, future research into VGSs will be increasingly multidisciplinary and will need to consider the interconnected dimensions of the system and how they determine both its cost and effectiveness. Highlights • Systematic review on VGS identified 1000 articles from Scopus and WoS; 166 articles included in final review. • Increasing research trend in VGS with 42 articles reviewed published in 2017, from 8 in 2010. • Included top ten journals publishing VGS research and top ten cited articles in VGS research. • Trend towards multidisciplinary research with growing number of articles relating to more than one discipline. • Identified emerging research and new technologies in VGS field. [ABSTRACT FROM AUTHOR]

Abstract The most commonly used interventions for energy requalification of buildings aim to increase the thermal resistance of the perimeter walls and ceiling and the efficiency of the HVAC system. Windows replacement is also usually foreseen. Moreover, the energy saving strategies have to reduce the energy consumption of the building, taking into account economic aspects and thermo-hygrometric comfort conditions of the occupants. In the case of historic buildings, some architectonical and urban planning restrictions impose to adopt only a few solutions that are well suited with the valuable architectural qualities of the building. In Italy, there are many historic buildings. They are often located in small towns, such as the case study of this paper, a public historic building, the library "G. Pascoli" placed in S. Severo (FG). In this paper, the authors propose an energy saving intervention, which consists in the application of a green wall on the back side of the building, being the principal façade subjected to architectural restrictions. The most suitable technological solution for the building considered has been proposed and a numerical analysis of the building's energy performance has been carried out by the software DesignBuilder. The results are satisfactory, being the energy consumptions significantly reduced both in summer and winter conditions. [ABSTRACT FROM AUTHOR]

Despite several studies showed that Vertical Greenery Systems (VGSs) have relevant thermal benefits at urban and building scales, researches devoted to investigate the benefits of a green facade through detailed transient thermal simulations are scarce. Furthermore, a study comparing the effectiveness of different plant types is still missing. The present paper aims to fill such gaps by studying the effectiveness of a green façade to improve the thermal behaviour of a well-insulated lightweight building in the Mediterranean area, as well as the perceived indoor thermal conditions, based on both on-site experimental measurements and dynamic thermal simulations with a novel Type in TRNSYS validated through the monitoring campaign. To this aim, two identical full-scale prefabricated modules were installed and monitored at the University Campus of Catania (Italy), differing from each other because one of them hosted a climbing plant species in its west façade. The validated numerical model was then used to appraise the cooling effect of the green façade with two different plant species commonly used in Mediterranean countries (Trachelospermum Jasminoides and Hedera Helix namely). Results show that Hedera helix ensures the best performance when the foliage layer is at an intermediate state of its growing process, while under full foliage development the species investigated show almost the same performance. The incoming heat flux can be strongly attenuated, showing a quite flat daily profile, while the peak value of the internal and external surface temperature of the wall can be reduced by up to 1.6 °C and 10.5 °C, respectively. • An experimental and numerical analysis of green façades in Mediterranean climate. • Accurate validation of an innovative vertical greenery system component in TRNSYS. • Simulations of Trachelospermum Jasminoides (Tj) and Hedera Helix (Hh) species. • Tj reduces the peak inner and outer surface temperature by 1.1 °C and by 7.4 °C. • Hh allows better performance when the foliage layer is at initial growing process. [ABSTRACT FROM AUTHOR]

The relationship between Urban Heat Island (UHI) and energy consumption in buildings has been widely observed and studied. The aim of this paper is to investigate the impact of large-scale deployment of indirect Vertical Greenery Systems (VGS) on the cooling demand of buildings and on the urban microclimate. VGS significantly reduces air temperature and wind speed near the walls. In doing so, it also positively impacts the UHI intensity. This is achieved mainly through the conversion of sensible heat to latent heat mediated by evaporation and transpiration from the VGS foliage. Evapotranspiration is a physically complex phenomenon and its interaction with the building and the urban climate is difficult to model accurately. We propose to use a dynamic nonlinear lumped parameter thermal network model to determine the thermal interactions between the prototypical building, the VGS, the paved road, the urban canopy air and the atmosphere. The model accounts for both sensible and latent exchanges within and outside the building. Solar (short-wave) radiation on building façade and road accounts for shading and unlimited diffuse reflections. Long-wave radiation among surfaces and between surfaces and the sky are estimated using view factors and the fully nonlinear Stefan-Bolzmann law. Building envelope infiltration rate and convective heat transfer coefficient vary with wind speed so as to properly reflect the energetic impact of wind speed attenuation near the wall due to the foliage. The thermal and aerodynamic characterization of the vegetation is based on the formulations proposed by Deardorff (1978). The evapotranspiration rate is estimated based on the Penman formula and is driven by the ‘vapor pressure deficit’ between actual vapor pressure in the ambient air and the saturation vapor pressure assumed to prevail on the surface of leaves. The calculation of sensible and latent heat fluxes between the urban canopy and the first level of the atmosphere considers buoyancy effects, using the coefficients introduced by Mascart et al. (1995). First, a base case model (no VGS) is created and validated using both building energy consumption data and urban air temperature measurements. The validated model is then used to investigate the impact of a large-scale deployment of VGS in the urban context. The weather data and the typical building thermo-physical properties are from the UAE. Comparison of the urban base case to the rural base case (both without VGS) shows a cooling load penalty, due to the UHI, of about 7 % . Retrofitting VGS to all buildings in the urban domain of study results in a 5 − 8 % reduction of the cooling load and a dramatic drop of the urban air temperature of about 0.7 − 0.9 °C, reducing the UHI intensity by almost half. [ABSTRACT FROM AUTHOR]

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. • Seeding of autochthonous meadow seed mixtures is a feasible way of creating attractive LWs. • A continuous fertilization and irrigation system is cost-efficient. • The meadow-LWs require one summer cut and removal of dead plant material in early spring only minimal maintenance. • The use of highly diverse seed mixtures is recommended to increase the number of establishing species with positive effects on biodiversity. [ABSTRACT FROM AUTHOR]

We quantified the transpiration cooling effect by comparing a living climber greenwall (CGW) against a real but non-transpiring one after confirming the cessation of transpiration and similar vegetation coverages of both of them. We severed stems of plants in one of the CGWs to stop transpiration. By monitoring the changes in transpiration rate, leaf temperature, and percentage coverages of plants with and without severance of stems, we tried to confirm the cessation of transpiration and similar vegetation coverages. In parallel with it, we measured the indoor thermal environments in the well-covered houses of the two treatments, as well as a non-covered house, and calculated the transpiration cooling effect. The transpiration rates of plants with stem severance dropped to less than 1.0 mmol m −2 s −1 within 35 min after severance. Almost all leaf temperatures in the severed treatment were similar to the dry reference leaf temperatures. In contrast, those in the non-severed treatment remained the same as before severance. In addition, the percentage points of percentage coverages between the living CGW and the real but non-transpiring one was reduced to just 1.5% two days after severance. Thus, we quantified the transpiration cooling effect of CGWs using the indoor thermal environmental data two days after severance. The average transpiration cooling effect calculated from the indoor wall surface temperatures (=severed plant-covered house − intact plant-covered house) was 0.23 °C, although the average shading cooling effect (=non-covered house − severed plant-covered house) was 8.55 °C under global solar radiation on a vertical south surface between 400 and 600 W m −2 . In addition, those calculated from room temperatures under the same environmental conditions were 0.15 and 4.00 °C, respectively. Therefore, we concluded that the transpiration cooling effect of CGWs, which were separately set from the walls, on the indoor thermal environment of houses was much smaller than the shading cooling effect. Using these methodologies, we recommend further investigation of the appropriate distance between CGWs and walls to increase the transpiration cooling effect. [ABSTRACT FROM AUTHOR]

Rapidly growing cities and human activities change the environment and are accompanied by some drawbacks. Sustainable remedies are needed to protect the environment and the earth against warming environment, pollution, natural resource use and other negative aspects of human activities. Applying vertical greenery systems not only reduce temperature, but also have many economic, environmental and social benefits. This review is about vertical greenery systems description, division and benefits with a focus on energy related topics. The paper describes different experiments on vertical greenery systems by attention to their energy characteristic from recent years. Scan research and studies have determined positive aspects of these sustainable systems as well as a few negative aspects. Moreover, different parameters which are involved in thermal performance of vertical greenery systems are highlighted. Based on various scan research some recommendations for future studies are proposed. [ABSTRACT FROM AUTHOR]

This review paper organizes and summarizes the literature on Vertical Greenery Systems (VGS) when used as passive tool for energy savings in buildings. First, with the information obtained in the reviewed literature some key aspects to consider when working with VGS are clarified, such as the classification systems, the climate influence, the plant species used and the different operating mechanisms. Then, the main conclusions of this literature, sorted by construction system (Green Walls or Green Façades) and climatic situation, are summarized. In general, it can be concluded that VGS provide great potential in reducing energy consumption in buildings, especially in the cooling periods. However, a lack of data on operation during the heating period as well as during the whole year has been found. On the other hand, results show that the investigations of VGS are not equally distributed around the world, being basically concentrated in Europe and Asia. Moreover, the review concludes that some aspects must be studied in depth, such as which species are the most suitable for each climate, influence on energy savings of the façade orientation, foliage thickness, presence of air layers, and finally, substrate layer composition and thickness in the case of green walls. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate a technique to cool livestock buildings by covering it with kudzu vine (Pueraria lobata). Specifically, we first examined whether one-year-old nursery stocks of kudzu that were planted in spring can cover livestock buildings with standard size by summer in Japan. Then, we quantified the cooling effects of changes of kudzu vine covering on the room temperatures of fabricated livestock buildings under field conditions. Our results showed that the vines reached the roof of standard-sized livestock buildings by summer. The estimated average percentage coverages and the sorted room temperature reductions (RTRs) showed positively significant relationships under the global solar radiation on a horizontal surface greater than 0.2 kW m-2. The maximum sorted RTR was 3.44 °C, when the estimated average percentage coverage was 43.9%. Thus, we conclude that the technique to cool livestock buildings using one-year-old nursery stocks of kudzu vine is applicable to livestock buildings. [ABSTRACT FROM AUTHOR]

Highlights: [•] Environmental performance of Vertical Greenery Systems is analysed based on eMergy. [•] ‘Environmental costs’ were assessed as the resource use for maintenance–sustenance. [•] ‘Environmental benefits’ refer to cooling energy saving due to the shading and airflow. [•] A ‘Cost to Benefit Ratio’ was calculated as an indicator of environmental performance. [•] In certain conditions environmental benefits were found to balance costs. [Copyright &y& Elsevier]

Abstract: Green façades have long been used to reduce the overheating of buildings by excessive solar gain, but little research attention has been paid to the plant traits that reduce the surface temperature of urban structures. This study aimed to identify the key traits contributing to the cooling effects of green façades by comparing five vine plant species. The vines were trained to climb a plastic net that was attached on the freestanding walls under outdoor conditions. One of the walls was not covered with plants to serve as control. We measured the longest vine length, total number of leaves, percentage coverage, leaf transpiration rate, leaf solar transmittance, wall surface temperatures, global solar radiation on a vertical south surface (GSR) and ambient temperature. We identified the percentage coverage as the key trait determining the overall cooling effect: a statistically positive relationship (P < 0.001) was identified between the percentage coverage and the wall surface temperature reduction (WTR; the wall surface temperature differences between the non-covered wall and the covered wall) under GSR of more than 0.1 kW m−2. The percentage coverage was in turn found to be determined by the vine length. We also found that genotypic differences in WTRs that were not explained by those in the percentage coverage were related to those in leaf solar transmittance, indicating that this trait also contributed to the cooling effects. [Copyright &y& Elsevier]