Search Results (39)

Green roofs are becoming common in cities around the world. Rooftop vegetation faces severe and unique conditions ranging from shallow substrates, high irradiance, water limitation, flooding, extreme temperatures, and strong winds. To benefit the most from this technology for improving urban climate, ecological interactions, and human life quality, it is important to have a toolbox of candidate plant species adapted to the rooftop environment. Herein, an effort was made to provide an overview of the global scenario of green roof plants. A quantitative and qualitative review examining 439 articles published within an approximate 14-year time window (2009 to mid-2023) was conducted to categorize plants amenable to use in green roof conditions, and to identify and discuss their key morphophysiological phenotypic features. This dataset allowed the establishment of archetypal green roof plants for use in different climates. Similar traits were recorded between temperate and continental climate species on one side and between tropical and dry climate plants on the other. The identified set of species and their archetypes within each major climate zone can be useful for readily adopting and expanding new green roofs and as a guideline for incorporating new taxa into this urban environmental technology. Full article

Traditional rooftop greenhouses offer a promising solution for urban vegetable supply but have the disadvantages of overheating during the daytime and supercooling during the nighttime. To address these issues, a novel solar greenhouse system using nanofluid spectral splitting and phase change materials (NSS-PCMs) was developed. In this study, a 75-day thermal environment test experiment was conducted on the novel solar greenhouse, and the growth status and nutrient composition of three typical plants were evaluated. By optimizing the greenhouse structure parameters through the model, over 80% of 300–800 nm wavelengths for vegetable photosynthesis were transmitted to the greenhouse, while the remaining spectrum was used for heat storage to maintain warmth during nighttime. The novel solar greenhouse reduced daytime temperatures by 5.2 °C and increased nighttime temperatures by 6.9 °C, reaching a maximum thermal efficiency of 53.4% compared to traditional greenhouses. The 75-day temperature detection showed that optimal temperature ranges were maintained for approximately 60 days, both during daytime and nighttime, with an 80% assurance rate. The growth rates of three vegetables in the novel solar greenhouse improved by 55%, 35%, and 40%, and the nutrient composition doubled compared to the control group. Full article

Green roofs (GRs) have been widely adopted as an effective Green Infrastructure (GI) practice in cities worldwide, offering ecosystem services such as stormwater management and reduction of the urban heat island effect. However, their widespread implementation is still limited by a lack of local research and uncertain research findings. As a result, the potential benefits of GRs often cannot justify their high investment costs. Previous studies have sought to enhance the effectiveness of GRs by evaluating new GR systems, such as integrating GRs with green walls, blue roofs, photovoltaic (PV) panels, radiant cooling systems, as well as the use of innovative materials in GR substrates. Biochar, a carbon-rich substrate additive, has been recently investigated. The addition of biochar improves water/nutrient retention of GRs, thereby increasing substrate fertility and promoting plant performance. Although studies have examined the effects of biochar on GR plant growth, long-term observational studies focusing on the impacts of various biochar-related parameters remain necessary. Therefore, this research aims to assess the performance of GR plants with different biochar parameters, namely, amendment rates, application methods, and particle sizes. A one-year-long observational data of plant height, coverage area, and dry weight from six GR test beds was collected and analyzed. Results demonstrate the positive impacts of biochar on plant growth in different biochar-GR setups and types of plant species (wallaby grass, common everlasting, and billy buttons). The GR with medium biochar particles at the amendment rate of 15% v/v had the best plant performance. This contributes to increasing the feasibility of GRs by maximizing GR benefits to buildings where they are installed while reducing GR costs of irrigation and maintenance. The conclusions were further supported by observed data indicating reduced substrate temperature, which in turn reduces building energy consumption. Since vegetation is crucial in determining the effectiveness of a GR system, this study will offer valuable insights to GR designers and urban planners for developing optimal biochar-amended GR systems. Such systems provide numerous benefits over traditional GRs, including enhanced plant growth, reduced building energy costs, a shorter payback period, and reduced structural requirements. Full article

Green roofs provide various ecosystem services, including habitats for diverse organisms in urban areas where natural space is very scarce. This study aims to evaluate the restoration effects of green roofs created by applying an ecological restoration method to reinforce habitat function. The reference ecosystem selected for the ecological restoration of a roof was a Korean red pine stand established on Mt. Bulam, considering the soil depth, light, moisture conditions, etc., compared with the roof’s environmental conditions. Ecological restoration was carried out by planting two-year-old pine seedlings and scattering surface soil collected from the pine stands. The pine trees showed geometrical growth in height and diameter and a high water-use efficiency. The ecological restoration of the green roofs demonstrated an ecological function for improving the urban climate through the mitigation of the urban heat island effect and high productivity, showing different functions depending on the greening method. The composition and diversity of vegetation and insects at the ecological restoration site were similar to those at the reference site, whereas the landscape architecture sites, which were created using the landscape architecture method, were different from the reference site. These results confirm that applying the ecological restoration method for rooftop greening resulted in better biological habitat function than applying existing landscape architecture methods. Full article

To mitigate the adverse impacts of urban stormwater on streams, watershed managers are increasingly using low-impact development and green infrastructure (LID-GI) stormwater control measures, such as rain gardens—vegetated depressional areas that collect and infiltrate runoff from rooftops and driveways. Their catchment-scale performance, however, can vary widely, and few studies have investigated the cumulative performance of residential rain gardens for event runoff control in intermediate-sized (i.e., 1–10 km²) suburban catchments. We modeled three years of continuous rainfall-runoff from a 3.1 km² catchment in Columbia, MD, USA, using the Storm Water Management Model (SWMM). Various extents of rain garden implementation at residential houses were simulated (i.e., 25%, 50%, 75%, and 100% coverage) to determine the effects on peak flow, runoff volume, and lag time. On average, treating 100% of residential rooftops in the catchment reduced peak flows by 14.3%, reduced runoff volumes by 11.4%, and increased lag times by 3.2% for the 223 rainfall events during the simulation period. Peak flow reductions were greater for smaller storm events (p < 0.01). Our results show that residential rain gardens can significantly improve the runoff response of suburban catchments, and that they represent an effective and relatively low-cost option for urban watershed management and restoration. Full article

Increased land use as a result of urbanization is one of the most rapid human-driven causes of biodiversity loss. Urbanization negatively affects human health because of poor nutrition, non-communicable diseases (NCDs) and health problems related to air pollution. Nature-based solutions (NbSs) for sustainable food production in combination with reduced land and water use are essential for the reduction in biodiversity loss, human health and nutrition. This systematic review aims to assess the effects of NbSs that positively contribute to biodiversity on human health and wellbeing in urban settings worldwide. Secondarily, other factors, such as safety, attractiveness, inequity and accessibility, that may have a potential role in the use of NbSs will be evaluated. For the purpose of the FENS conference, only results related to nutrition and food security will be presented. The PRISMA guidelines will be followed. Full-length articles in English language conducted in 2000 and published in 2010 will be included. Both quantitative and qualitative studies are eligible. Due to the diversity of studies, the quality assessment with diverse studies (QuADS) tool will be used for the quality assessment of the studies included. The statistical analysis will depend on the heterogeneity and the feasibility of harmonization of the data. PubMed, Web of Science and Scopus were searched. The initial search yielded 14386 publications. After the removal of duplicates, 8730 titles and abstracts were screened. Currently, 881 full texts out of 2928 have been screened, from which 69 (8%) studies reported outcomes related to human nutrition and food security. Most of the studies took place in urban gardens (61%). Urban farming (25%) and farmers’ markets followed (25%). Vegetation/greenness in cities was considered as an NbS by 6% of the studies. Less studied NbSs were green roofs, general green spaces, urban foraging and urban blue spaces (3% each). Gardening has been shown to be beneficial for the wellbeing and nutrition of various populations. Due to the high land use for the feeding of urban populations, alternative food production techniques without soil use are important. Soil-free rooftop farms and vertical farming could increase the vegetable and fruit production in cities and improve the diet quality of citizens. Full article

The use of solar energy has shown the fastest global growth of all renewable energy sources. Efforts towards careful evaluation are required to select optimal locations for the installation of photovoltaics (PV) because their effectiveness is strongly reliant on exposure to solar irradiation. Assessing the shadows cast by nearby buildings and vegetation is essential, especially at the city scale. Due to urban complexity, conventional methods using Digital Surface Models (DSM) overestimate solar irradiation in dense urban environments. To provide further insights into this dilemma, a new modeling technique was developed for integrated 3D city modeling and solar potential assessment on building roofs using light detection and ranging (LiDAR) data. The methodology used hotspot analysis to validate the workflow in both site and without-site contexts (e.g., trees that shield small buildings). Field testing was conducted, covering a total area of 4975 square miles and 10,489 existing buildings. The results demonstrate a considerable impact of large, dense trees on the solar irradiation received by smaller buildings. Considering the site’s context, a mean annual solar estimate of 99.97 kWh/m²/year was determined. Without considering the site context, this value increased by 9.3% (as a percentage of total rooftops) to 109.17 kWh/m²/year, with a peak in July and troughs in December and January. The study suggests that both factors have a substantial impact on solar potential estimations, emphasizing the importance of carefully considering the shadowing effect during PV panel installation. The research findings reveal that 1517 buildings in the downtown area of Austin have high estimated radiation ranging from 4.7 to 6.9 kWh/m²/day, providing valuable insights for the identification of optimal locations highly suitable for PV installation. Additionally, this methodology can be generalized to other cities, addressing the broader demand for renewable energy solutions. Full article

Buildings are important components of urban areas, and the construction of rooftop photovoltaic systems plays a critical role in the transition to renewable energy generation. With rooftop solar photovoltaics receiving increased attention, the problem of how to estimate rooftop photovoltaics is under discussion; building detection from remote sensing images is one way to address it. In this study, we presented an available approach to estimate a building’s rooftop solar photovoltaic potential. A rapid and accurate rooftop extraction method was developed using object-based image classification combining normalized difference vegetation index (NDVI) and digital surface models (DSMs), and a method for the identification of suitable rooftops for solar panel installation by analysing the geographical restrictions was proposed. The approach was validated using six scenes from Beijing that were taken using Chinese Gaofen-2 (GF-2) satellite imagery and Pleiades imagery. A total of 176 roofs in six scenarios were suitable for PV installation, and the estimated photovoltaic panel area was 205,827 m². The rooftop photovoltaic potential was estimated to total 22,551 GWh. The results indicated that the rooftop photovoltaic potential estimation method performs well. Full article

Good appearance throughout the year is important for perennial ornamental plants used for rooftop greenery. However, the methods for evaluating appearance throughout the year, such as plant color and growth activity, are not well understood. In this study, evergreen and winter-dormant parents of Phedimus takesimensis and 94 F₁ plants were used for multispectral imaging. We took 16 multispectral image measurements from March 2019 to April 2020 and used them to calculate 15 vegetation indices and the area of plant cover. QTL analysis was also performed. Traits such as the area of plant cover and vegetation indices related to biomass were high during spring and summer (growth period), whereas vegetation indices related to anthocyanins were high in winter (dormancy period). According to the PCA, changes in the intensity of light reflected from the plants at different wavelengths over the course of a year were consistent with the changes in plant color and growth activity. Seven QTLs were found to be associated with major seasonal growth changes. This approach, which monitors not only at a single point in time but also over time, can reveal morphological changes during growth, senescence, and dormancy throughout the year. Full article

Utilizing idle space for agricultural planting can generate production profits while greening the urban environment. How can the space available for agricultural planting in cities be inventoried and quantified, and what is the production potential? With the help of GIS, spatial analysis was carried out, and more objective conclusions were drawn through calculation. This paper takes the roof space in Shibei District of Qingdao as an example to study: First, we analyzed the influencing factors and inventory standards of roof agricultural planting; second, we selected inventory standards for idle roof space inventory and conducted statistical analysis of the data obtained from the inventory. Furthermore, combining the annual yield of vegetables per unit area and the annual consumption standards of vegetables by citizens, we calculated the yield and supply and demand; next, we summarized the research results, analyzed their reliability and the advantages and disadvantages of this inventory, and derived formulas for calculating the agricultural production potential of rooftops and urban spaces. Finally, we concluded that the idle roof area in cities and the potential for agricultural production are significant. The research results indicate that the roof area of urban buildings in the Shibei District of Qingdao is 383.3 hectares, with an annual vegetable production potential of 25,800 tons, which can supply the urban population of 184,300. Based on the above research, it is proposed that rooftop agriculture should be given priority in the future development of urban agriculture, and it is recommended that other urban spaces should be inventoried to promote the development of urban agriculture. Full article

This paper responds to the research question, “can urban farming in Nepal help create sustainable cities?” Especially after the COVID-19 pandemic, urban residents have begun to realize that food transported from long distances is not always reliable. Urban farming can help produce fresh food locally and help urban residents become self-reliant by engaging in healthy eating habits and practicing sustainable agricultural techniques in food-desert areas, while creating a positive impact on the environment through regenerative agricultural methods. In doing so, urban farms can help the growers save on food expenditures and even earn some additional income, while also improving air quality and minimizing the effects of urban heat islands. This practice also helps reduce greenhouse gases through plant carbon use efficiency (CUE), as vegetation carbon dynamics (VCD) can be adjusted while supporting the circular economy. As urban lands command higher prices than agricultural land, urban farming usually happens on residential yards, roofs, balconies, community gardens, and dedicated areas in public parks. Rainwater harvesting and redirecting can help irrigate urban farms, which can be part of rain gardens. The national census of 2021 identified that 66% of Nepal’s population lives in urban areas. However, the World Bank (2018) showed that only 21 of Nepal’s population was projected to live in urban areas in 2021. It is not debatable that the urbanization process in Nepal is on the rise. Thus, urban agriculture can play an important role in supplementing residents’ food needs. Many cities in Nepal have already successfully adapted to urban farming wherein residents grow food on their building sites, balconies, and rooftop, often growing plants in pots, vases, and other types of containers. The UN-Habitat, with the support of the European Union and local agencies, published a rooftop farming training manual (2014), showing the feasibility of urban farming in Nepal. This paper discusses how public-private partnership (PPP) can promote urban agriculture and make the process more effective and attractive to urban-farming households. It also analyzes how a PPP approach also facilitates the use of better technology, advisory support, and use of research extension activities. This paper draws on a literature review, uses remote-sensing imagery data and data from National Census Nepal 2021, and the authors’ professional experiences related to best practices in the areas to analyze the benefits and challenges related to urban farming both in Nepal and Arizona, USA. The paper provides recommendations for Nepali cities to maximize the benefit provided by urban farming. It is expected to be useful to Nepali policymakers, government agencies, and nonprofit organizations which promote sustainability, and organic farming with a sustainable supply chain. Full article

This paper presents two uniform theories of diffraction–physical optics (UTD-PO) formulations to undertake analysis of radiowave multiple diffraction resulting from the presence of both buildings and trees in vegetated urban areas, with the assumption of spherical-wave incidence. The solutions presented consider buildings modeled as knife-edges and rectangular sections (the latter being more complex and realistic) and the effect of the tree canopy (the assumption is that this exceeds the height of the average rooftop) is taken into account by adding proper attenuation factors/phasors to building diffraction phenomena. The validation of these formulations has been undertaken by comparing with other methods and measurements performed at 39 GHz on a scaled-model of the environment under analysis, consisting of an array of bricks and bonsai trees. The chief advantage of the solutions put forward is that because of recursion, the calculations only include single diffractions. This avoids any requirement for higher-order diffraction terms in the diffraction coefficients, which means less computer time/power is demanded. The results of this work may be useful when planning future mobile communication systems, including 6G networks and beyond. Full article

Connectedness to nature has been recognized as an important factor for well-being, with rooftop green spaces being used for stress reduction in modern cities. This study aimed to examine psychological and physiological responses to three different vegetation models on an urban rooftop. An analysis of psychological parameters indicated that the existence of vegetation in rooftop spaces could have positive effects on mood states, and the size of the effect was greater in a structured vegetation design than in a monotonous one. An analysis of the physiological parameters of heart rate variability and systolic blood pressure indicated that greater restorative effects are elicited from the use of vertical elements, such as shrubs and trees, added to grassy areas than from concrete environments. However, a fully enclosed vegetation with trees was not associated with higher parasympathetic activities than a half-open vegetation model. Based on these findings, an open and structured vegetation design that includes both grass and shrubs may have more potential for stress reduction than a monotonous vegetation model. A larger volume of vegetation was not necessarily linked to higher psychological and physiological benefits. Full article

The metabolism of a building can be connected to a rooftop greenhouse, exchanging energy, water and CO₂ flows, therefore reducing emissions and recycling cultivation inputs. However, integrating a rooftop greenhouse onto a building requires the application of stringent safety codes (e.g., fire, seismic codes), to strengthen and secure the structure with safety elements such as thick steel pillars or fireproof covering materials. These elements can shade the vegetation or reduce solar radiation entering the rooftop greenhouse. Nevertheless, application of additional LED light can help to overcome this constraint. The present study evaluated supplemental LED light application in an integrated rooftop greenhouse (i-RTG) at the ICTA-UAB research institute, located in Barcelona (Spain), for tomato cultivation (Solanum lycopersicum cv. Siranzo). The experiment explored the effects of three LED lighting treatments and a control cultivated under natural light only (CK). Applied treatments, added to natural sunlight, were: red and blue (RB), red and blue + far-red (FR) for the whole day, and red and blue + far-red at the end-of-day (EOD), each for 16 h d⁻¹ (8 a.m.–12 a.m.) with an intensity of 170 µmol m⁻² s⁻¹. The results indicate that LED light increased the overall yield by 17% compared with CK plants. In particular, CK tomatoes were 9.3% lighter and 7.2% fewer as compared with tomatoes grown under LED treatments. Fruit ripening was also affected, with an increase of 35% red proximal fruit in LED-treated plants. In conclusion, LED light seems to positively affect the development and growth of tomatoes in building integrated agriculture in the Mediterranean area. Full article

Heat island effects raise the ambient air temperature in metropolitan areas by 4–5 degrees Celsius and can reach 10 degrees Celsius at their maximum. This phenomenon magnifies cities’ energy difficulties while reducing comfort. Mitigation strategies have been developed and recommended to deal with the issue. Methods to increase albedo and the utilisation of vegetation appear to be the most promising, with a reasonably high heat island reduction capacity. This paper examines the heat mitigation techniques and their effectiveness under Sydney’s climate conditions and compares strategies. We implement two perspectives, namely urban greening (green roofs, green pavements) and albedo (street, roof), and characterise urban surface structures, and Envi-met software is employed for our simulation method. Mitigation strategies show a cooling potential of 4.1 °C in temperature along this precinct during the heatwave period. Scenarios that increase high-albedo material on the road, pavements and rooftops and full mitigation show the maximum cooling potential. The mitigation strategies have higher predicted cooling potential on the peak ambient temperature, up to 1.18 °C, while having no or little impact on minimum ambient temperature. The outdoor thermal comfort based on PMV indices varies between a minimum of −0.33 in scenario seven in large layout areas to 3. However, the mitigation scenario presents more acceptable outdoor thermal comfort, but large layouts are predicted to have a hot condition. Full article