Research & reports

Chandni Singh, Sheetal Somashekar Patil, Swarnika Sharma · Environmental Research Climate · India

As urban heat increasingly affects liveability, labour productivity and human health, nature-based solutions such as green roofs, increased urban tree cover and dedicated park space have been proposed to adapt to rising urban heat, but the literature has paid relatively little attention to how smaller urban green spaces — fragmented urban greenery and rooftop home gardens — contribute to hyperlocal temperature regulation. This study examined whether rooftop home gardens in Bangalore, India, regulate indoor temperature and provide thermal comfort, drawing on perception-based data from household surveys and in-depth interviews alongside modelled scenario data covering different types of rooftop home gardens. People generally perceived thermal comfort in rooms directly below rooftop farms/gardens, and reported air-conditioner use declined after starting rooftop gardening. Modelling across seven scenarios, from no green cover to complete (100%) soil-bed cover, showed heat reduction benefits ranging from 1.5°C to 14°C depending on foliage type, density and extent of green cover; because most rooftops serve multiple purposes, the study identifies a more realistic temperature reduction of 1.5°C to 3°C, corresponding to a scenario with 50% of the roof covered in dense foliage.

Alfiya Rokhmah, Ririn Mulyani, Muhammad Yusuf Hamdhani, Doni Doni · Jurnal Keteknikan Pertanian · Indonesia

At Universitas Sains Indonesia in Cibitung subdistrict, Bekasi Regency, Indonesia, researchers designed an urban farming layout to increase green open space on limited campus land. Using a mixed-method approach combining site analysis, field observation, facility-relationship analysis and economic feasibility estimation, the proposed design combines an aquaponic system (a 1,000-liter fish tank linked to hydroponic pipes with 120 planting holes), a vertical farming system adding 60 planting holes, and a green-learning park. The initial investment was estimated at approximately Rp 12,270,000 with relatively low operating costs, and the system was projected to yield 37-45 kg of vegetables per month and 30-40 kg of fish per production cycle.

D Darto, Nunung Cipta Dainy, Helfi Gustia, Raisa Ardiyanti, Farah Aurellia Sasikirana, Niken Wulandari Dyrin, Graiseld Raissa Erwanto · DOAJ (DOAJ: Directory of Open Access Journals) · Indonesia (Jakarta)

A community outreach activity carried out in August-September 2025 with the Hidroponik Generik farming group in Pesanggrahan, Jakarta, Indonesia, introduced an IoT-integrated solar power system and accompanying equipment, training and mentoring to reduce the electricity costs of a hydroponic system. An 800 Wp solar panel generating 1,400 Wh per day was confirmed able to power a rack-based hydroponic system with 1,000 planting holes, IoT monitoring let partners track water quality via smartphone, and the program reported cutting electricity operating costs by 30%.

Tianqi Su, Yongmei · Agriculture · China

Based on multitemporal remote-sensing data from 1985 to 2015, this study examined the evolution of urban-agricultural-ecological spatial structure and water-heat-vegetation responses driven by large-scale irrigation and drainage projects in the Inner Mongolia Hetao Plain, an arid/semi-arid region of China. It built a "multifunctionality-dynamic evolution" dual-principle classification system, combining maximum-likelihood classification of individual land types with conflict-pixel-resolution merging to achieve 90.82% classification accuracy, and used a land-use transfer matrix, a standard deviation ellipse model, land surface temperature (LST) inversion, and vegetation fractional coverage (VFC) analysis. The results showed: (1) spatial structure followed a path of short-term intense disturbance followed by long-term stable optimization, with agricultural space stability increasing 4.8%, ecological core area retention exceeding 90%, and urban space expansion shifting from external encroachment to internal filling; (2) VFC increased steadily in the central area (0.8% annual growth), fluctuated with recovery in the eastern area (±12% cyclic amplitude), and improved locally in the western area (key patches up 18%); (3) the LST-VFC relationship showed spatiotemporal misalignment, with 0.8-1.2°C anomalous cooling in the central region during construction despite a 15% VFC decrease, driven by irrigation water's thermal inertia, and a disrupted linear correlation after completion due to changes in crop phenology and plastic film mulching; and (4) the irrigation and drainage projects optimized water resource allocation, constructing a hub regulation model integrated with the Water-Energy-Food (WEF) Nexus.

Pungky Slamet Wisnu Kusuma, Dyah Hariani, Vivin Andriani, Dicky Surya Putra Pradana Andriani · Jurnal Abadimas Adi Buana · Indonesia

Describes a community-service (PKM) activity centered on an NFT (Nutrient Film Technique) aquaponics system, framed as an urban-farming innovation supporting sustainable urban food security. The activity aimed to analyze the NFT aquaponic system's efficiency and to increase student and public understanding of it through a national webinar. It reports that the NFT system reduced water use by 80-90% compared with conventional systems through closed-loop recirculation, and that integrating catfish (Clarias sp.), water spinach (Ipomoea aquatica) and nitrifying bacteria created a productive system supporting a zero-waste concept. Webinar evaluation showed participant understanding rising by 26 percentage points, from 62% to 88% after the session, with participants reported to show high interest in smart-farming aquaponics applications.

Siti Nurul Khotimah, Ihsanuddin Fadillah, Martinus · Nemui Nyimah · Indonesia

A participatory education program for household-level climate adaptation was delivered to seven housewives belonging to the Rumah Keluarga Indonesia community. The curriculum covered climate change impacts on food production, water and energy availability, the use of home yards for food production through urban farming with household organic waste, and simple technologies such as small solar panels for yard lighting. Following the activity, participants showed strong engagement and reported increased understanding and awareness of women's role in household food, water and energy resilience to climate change.

Dominik Bittner, Joanne U Smith, Georgios Leontidis, Grant Campbell, Jeanne Biegel, Pete Smith, Matthias Kuhnert, Rastislav Skalský, Licida M. Maria Giuliani, Abdul Walid Walid Salik, Paul Hallett, D Burslem, Getahun Yakob, Wolde Mekuria, Euan Phimister, Amare Haileslassie, Desalegn Tegegne, sarem norouzi, Heyu Chen, Cecile Gubry-Rangin, Adnan Khan · Environmental Research Letters · Sub-Saharan Africa

A narrative review examines tools for assessing soil health and Nature-based Solutions (NbS) for soil quality in sub-Saharan Africa, drawing primarily on examples from Ethiopia but intended for farmers and advisors across the region and other developing countries. It reviews physical, biological, chemical, functional, and service-related soil tests, noting that science-based tests require expertise, equipment, and cost, while locally-derived tests are affordable and readily applicable. NbS practices are assessed against labor, cost, and crop-production factors, and the review concludes there is no single universally applicable practice — suitability depends on farmers' priorities and circumstances. It also examines predictive methods, including mechanistic soil models, AI, and hybrid approaches combining data, physics, and knowledge such as digital soil mapping.

Ana Paula Branco do Nascimento, Rafael Silva de Araújo, Thais Reis Rocha, Ramoel Serafini · Revista Nacional de Gerenciamento de Cidades · Brazil

This applied, exploratory-experimental study designed and implemented a rainwater harvesting and irrigation automation system for food plant beds at a community garden ("Horta das Flores") under an impermeable roof in the eastern region of São Paulo, Brazil, aiming to reduce dependence on manual irrigation by volunteers. Developed through literature and technical review, field measurements, hydraulic efficiency tests, and component adjustments, the system was found to be technically and operationally feasible, ensuring regular water supply while reducing manual effort, and field evaluation enabled further hydraulic improvements and automation adjustments.

Akhil S Anand, Hannes Pravida, Fredrik Fossan-Waage, Tormod Skorpe Skjolden, Giulia Robbiani, Younes Zahraoui, Emil Wolff Anthony, Jayaprakash Rajasekharan, Sissel Torre, Knut Asbjørn Solhaug, Sebastien Gros · Frontiers in Horticulture · Global

A paper on vertical farming — a controlled-environment agriculture system — examines its potential integration with energy markets. It states that vertical farming's economic viability is constrained by high capital and operational costs, a substantial share of which is energy expenditure, and explores how vertical farms could participate in day-ahead, balancing, and flexibility energy markets by adjusting lighting and climate-control energy use in response to market signals, potentially reducing costs and generating additional revenue. It identifies gaps in understanding of plant responses to variable lighting as a critical barrier to implementation and illustrates these integration challenges through small-scale laboratory experiments.

Agure E, Kihagi GW, Muok EMO, Sorgho R, Danquah I · Journal of Health, Population and Nutrition · ケニア・シアヤ郡

A qualitative study of a home gardening intervention in Siaya county, rural Kenya, undertaken because home gardens are promoted as a climate change adaptation strategy in sub-Saharan Africa but the lived experience of them is less documented. Between September and November 2023 the authors ran two focus group discussions with stakeholders (n = 5) and implementers (n = 8), plus 30 in-depth interviews with male (n = 5) and female (n = 25) beneficiaries, using purposive sampling and semi-structured guides; data were transcribed verbatim and analysed by inductive content analysis mapped along the proposed impact pathways. Participants articulated a good understanding of the trainings and valued them as an occasion for knowledge exchange, and the adoption of tailored garden structures, organic gardening and food preservation created feelings of fulfilment, women's empowerment and family peace. Challenges included water scarcity, ineffective pesticides and long distances between beneficiary households. Perceived benefits were increased income, cost savings and increased dietary diversity.

Md. Nur Alom Sarkar Mithun, Saifur Rahman, Md. Asifur Rahman, Md. Hasan Sabit, Joseph L. Donaldson, Shonia Sheheli · Urban Agriculture & Regional Food Systems 11(1) · Bangladesh (Mymensingh — Kewatkhali and Aqua)

A study of perceived barriers among 100 randomly selected rooftop gardeners in Kewatkhali and Aqua, Mymensingh, Bangladesh, interviewed with a structured protocol between September and November 2023 and analysed with descriptive statistics, rank order, correlation coefficients and multiple linear regression. Every participant perceived substantial barriers. The most prominent concern was the complexity of the technologies involved; neighbours' negative attitudes ranked least significant. Age, rooftop garden area, income, experience, contact with extension media and gardening knowledge were all negatively and significantly related to perceived barriers, with garden area and knowledge the strongest predictors in the regression. The authors argue that research, demonstrations, extension activity and training to build residents' skills and understanding are the way to lower those barriers.

US Environmental Protection Agency (EPA) · US Environmental Protection Agency (EPA) · United States

EPA's overview page for the Renewable Fuel Standard (RFS) program, created under the 2005 Energy Policy Act and expanded by the 2007 Energy Independence and Security Act, aimed at reducing greenhouse gas emissions, expanding the domestic biofuels sector, and reducing reliance on imported petroleum.

U.S. Environmental Protection Agency (EPA) · U.S. Environmental Protection Agency (EPA) · United States

This EPA page explains that green roofs can lower surface temperatures by up to 56°F, nearby air temperatures by up to 20°F, and indoor air temperatures by 27°F compared to conventional roofs, while cutting cooling loads by up to 70% and reducing runoff by 60-100%. The industry grew 5-15% from 2013-2019, with 763 projects covering more than 3.1 million square feet installed in 2019.

Evangelista et al. · Agronomy for Sustainable Development · Europe

This 8-year case study tracked tomato cultivation in a rooftop greenhouse. Peak yield reached 49 g plant−1 day−1 in the 2023 cycle, but overall yield declined by 31.2% across the 8 years. Best water use efficiency reached 36.8 g/L under reduced irrigation. Solar transmittance dropped from 50.9% in 2015 to 46.4% in 2023 due to polycarbonate degradation, and life-cycle global warming impact rose from a minimum of 0.54 kg CO2eq to 0.94 kg CO2eq in 2023.

· Wikipedia · Global

This article describes green roofs as roof structures covered with vegetation and growing media that provide stormwater retention, insulation, urban heat island mitigation, and biodiversity benefits. Installation costs vary widely by system type, from $108-248/m2 for extensive systems to $355-2,368/m2 for intensive systems, with long-term economic benefits such as extended roof lifespan and increased property value offsetting high upfront costs.

· Wikipedia (German) · Germany

This article on green roofs in Germany explains that some major cities subsidize up to 50% of installation costs, and reduced stormwater fees (averaging €0.46/m2/year, up to €1.12/m2/year in Cologne) are also used to encourage adoption. Green roofs can be mandated in municipal development plans and used as ecological compensation measures, with about 8 million m2 newly greened annually nationwide, over 80% of it extensive systems.

· Wikipedia · Europe

Le Corbusier's 'Five Points of a New Architecture,' presented in 1927 and revised in 1929, comprise pilotis, the roof garden, the free plan, the horizontal (ribbon) window, and the free façade. The roof garden was framed as opening the roof to 'systematic domestic use,' and was realized in buildings such as Villa Savoye (completed 1931).

国土交通省 · 国土交通省 都市局公園緑地・景観課 · Japan

This MLIT Urban Bureau page introduces rooftop and wall greening promotion measures implemented annually since fiscal 2000. As of the end of March 2008, rooftop greening in Tokyo's Kasumigaseki government district reached about 14,500 sqm (roughly 55 tennis courts), equivalent to about 1.5% of all rooftop-type greened area in Tokyo. It notes a rooftop garden was open to the public until August 19, 2021, after which it was scheduled for removal due to waterproofing layer repair work.

United States Environmental Protection Agency · US Environmental Protection Agency (EPA) · United States

The EPA's Soak Up the Rain page states that green roofs can significantly reduce the amount of rainwater that would otherwise run off an impervious roof surface, and can also help reduce building energy usage and noise while increasing roof durability and lifespan compared to conventional roofs. It explicitly notes that structures must be able to support the loading of green roof materials under fully saturated conditions.

· Wikipedia（日本語版） · Japan

The Japanese Wikipedia article on rooftop greening traces its origins to the Hanging Gardens of Babylon around 600 BCE, and in Japan cites the 1934-built Asakura Museum of Sculpture as a surviving early example, with Nihonbashi Takashimaya among the pioneers from the late 1960s onward. It lists effects including heat island mitigation, improved insulation, sound reduction, increased water retention, air purification, and improved landscape, dividing methods into lightweight thin-layer greening using sedum or lawn versus full garden-style greening with flower beds and shrubs.

· Wikipedia · Cuba

This Wikipedia article covers Cuba's 'Special Period' economic crisis following the Soviet Union's collapse. Oil imports fell to about 10% of pre-1990 levels, GDP shrank 35%, and imports and exports both fell over 80%. Agricultural production fell 47%, construction fell 75%, and manufacturing capacity fell 90%, driving the need for agricultural transformation.

· Wikipedia · Global

This Wikipedia article on the Haber (Haber-Bosch) process for industrial ammonia synthesis states that, as of 2018, the process produced 230 million tonnes of anhydrous ammonia per year, and that 'nearly 50%' of the nitrogen found in human tissues originated from it. Ammonia production is said to account for 1-2% of global energy consumption, 3-5% of natural gas production, and 3% of global carbon emissions, while nitrogen use efficiency is typically less than 50%, with farm runoff from excess use disrupting biological habitats. The article also credits the process with supporting global population growth from about 2 billion in the early 20th century to over 8 billion today.

· Wikipedia · Global

This Wikipedia article on nitrogen fixation (the chemical process converting inert nitrogen gas into biologically usable nitrogen compounds) states that, as one legume example, nitrogen fixation by red clover can range from 50 to 200 lb/acre (56 to 224 kg/ha). It states the marine cyanobacterium Trichodesmium is thought to account for 'almost half' of nitrogen fixation in marine systems globally, and that the amount of nitrogen fixed in the ocean is at least as much as on land. It also credits the spread of Haber-process nitrogen fertilizer with helping expand the human population from about 2 billion in the early 20th century to over 8 billion today.

Stichting DakAkker · Stichting DakAkker (official) · Netherlands

The official site of DakAkker, a rooftop farm on top of the Schieblock building in Rotterdam. It describes itself as a 1,000-square-meter rooftop farm growing vegetables, edible flowers, and fruit and keeping bees, calling itself the largest open-air rooftop farm in the Netherlands and one of the largest in Europe. It is presented as an initiative of ZUS (Zones Urbaines Sensibles) and the Rotterdam Environmental Centre together with Optigrün Benelux and binder daktuinen, framed as part of Rotterdam's first city initiative 'de Luchtsingel.' The roof also hosts 'Slimdak,' a test site for smart rainwater management. 'Dakennie,' its environmental education program for Rotterdam primary schools, is financially supported by Watersensitive Rotterdam, the City of Rotterdam's nature and environmental education division, and the Hoogheemraadschap Schieland en de Krimpenerwaard water authority. The page itself does not state an opening year, which could not be confirmed here.

· Wikipedia · Netherlands

A floating dairy farm in the harbour of Rotterdam, described by its founders Peter and Minke van Wingerden as the world's first. It opened on May 13, 2019 with 32 cows, with plans to grow to 40. It is designed to use residual city products such as park grass and food waste to feed the animals, processes raw dairy into milk and yoghurt onsite for distribution in the city, and returns cow manure as fertilizer for public spaces. All power comes from solar panels, rainwater is collected on the roof, and milking, manure cleanup, and feeding are largely automated.