Research & reports

三鷹市 · 三鷹市 · Japan

Mitaka City's greening subsidy covers up to half the actual cost of rooftop greening work, capped at 20,000 yen per square meter (with a combined cap of 1 million yen for rooftop and wall greening together). Wall greening is subsidized up to 10,000 yen per square meter, and street-facing greening up to 14,000 yen per meter. Applicants must obtain approval before starting work, and sites that received the subsidy within the past five years are ineligible.

農林水産省 · 農林水産省 · Japan

This MAFF page explains that community gardens (shimin nouen) in Japan can be established by municipalities, agricultural cooperatives, landowning farmers, or non-landowning entities such as companies and NPOs, under three legal frameworks: the Community Garden Development Promotion Act, the Specified Farmland Lease Act, and the Urban Farmland Lease Act. It is primarily procedural guidance for prospective operators, with a FY2026 explanatory pamphlet available.

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 · United States

Brooklyn Grange operates 5.6 acres of organic vegetable and honey production across three rooftop farms in New York City, the largest rooftop farm operation in the city. Founded in 2010, it produces about 80,000 pounds of vegetables and roughly 1,500 pounds of honey annually. The founders launched the business with loans, personal savings, and investors, and the Brooklyn Navy Yard farm was partly funded by a $592,730 grant from the NYC DEP Green Infrastructure Grant Program.

· 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 · Canada

Lufa Farms is an urban agriculture company founded in 2009 in Montreal, Canada, that operates commercial hydroponic greenhouses on building rooftops. It runs four rooftop greenhouses, employs about 200 people, and delivers roughly 20,000 baskets weekly to more than 500 pickup points across Quebec.

台東区 · 台東区 · Japan

Taito Ward partners with Daimaru Matsuzakaya and Local Food Cycling to sell subsidized home compost containers and run collection events for circular food-waste use. Over the one-year period from December 2024 to November 2025, the ward reports about 5.4 tons of food waste reduction and about 2.6 tons of CO2 reduction.

· Wikipedia · United States

Gotham Greens is a U.S. company founded in 2009 by Viraj Puri and Eric Haley that grows lettuce, herbs, and related products via hydroponics in rooftop greenhouses. Its first greenhouse (15,000 sq ft) opened in Brooklyn in May 2011, and as of 2026 it operates 13 facilities totaling over 1.8 million square feet across New York City, Chicago, and other states. The company claims up to 30 times the production efficiency per acre versus conventional field agriculture, up to 90% less water use, and 97% less land use, and raised $310 million in 2022 (cumulative funding of $440 million).

· 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).

· Wikipedia · United Kingdom

Kensington Roof Gardens is a roughly 6,000 sq m garden atop the former Derry & Toms department store building, designed and built between 1936 and 1938 by landscape architect Ralph Hancock, comprising three themed gardens: a Spanish garden, a Tudor-style garden, and an English woodland garden with a stream and pond. The trees received a tree preservation order in 1976, the garden was Grade II listed in 1998, but public access ended in 2018; after a 2021 acquisition, it reopened in 2024 as a private members' club.

· Wikipedia · United States

A rooftop garden designed by Ralph Hancock and Raymond Hood opened on the 11th floor of 30 Rockefeller Plaza in April 1935. It originally featured themed gardens representing 13 nations (the 'Gardens of the Nations'), which were demolished by 1938; the garden subsequently died off and was replaced by a non-public flower bed, and no longer exists today.

· Wikipedia · United States

The rooftop garden at the Kaiser Center in Oakland (building completed 1960) was commissioned after the building's design and created by Theodore Osmundson & Associates, a San Francisco landscape architecture firm. It was inspired by the gardens at Rockefeller Center and is described as the first rooftop garden built in the United States after World War II.

· Wikipedia (ja) · Japan

Japanese department store rooftop amusement parks trace back to Nihonbashi Mitsukoshi's 'aerial garden' in 1907, with Japan's first permanent rooftop amusement park, 'Sportsland,' opening at Matsuya Asakusa in November 1931. They peaked from the mid-1950s through the late 1960s, but declined after department store fires in 1972 and 1973 led to a revised Fire Service Act requiring half of rooftops to be kept as evacuation areas; as of 2023, only five stores—Matsuzakaya Takatsuki, Matsuzakaya Nagoya, Daiwa Korinbo, Iyotetsu Takashimaya, and Hamaya Department Store—still operate one.

· Wikipedia (ja) · Japan

The Ginza Honeybee Project began on March 28, 2006, keeping Western and Japanese honeybees on Ginza building rooftops, producing and selling honey-based sweets, cocktails, and soap, greening over 1,000 sqm of rooftop space, and providing environmental education to local kindergartens and schools. Honey production grew from 150 kg in 2006 to 800 kg in 2009, and an agricultural production corporation, Ginza Mitsubachi, was established in 2010.

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 (English) · Global

According to this English Wikipedia article, expanded clay aggregate (LECA) is produced by heating clay to around 1,200C in a rotary kiln, causing trapped gases to expand into a porous, rounded structure, available in sizes from 0.1mm to 25mm and densities of 250-510 kg/m3 (up to 500 kg/m3 for large LECA boulders). It offers thermal insulation (thermal conductivity as low as 0.097 W/mK), acoustic performance, moisture and fire resistance, and in hydroponics serves as a growing medium providing root aeration while retaining water and nutrients.

· 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 (English) · Cuba

According to English Wikipedia, organoponicos emerged as urban farming in Cuba during the 'Special Period' after the 1989 Soviet collapse cut off chemical inputs, responding to a food crisis in which daily per-capita calorie intake fell from 2,900 in 1989 to 1,800 by 1995. As of 2009 over 35,000 hectares were in use in Havana alone, producing 280 grams of fruit and vegetables per resident per day, with the Havana workforce growing from 9,000 in 1999 to 23,000 in 2001 and over 44,000 by 2006.

· Wikipedia · Global

The English Wikipedia article 'Permaculture' defines it as an approach to land management and design based on observing flourishing natural ecosystems. Franklin Hiram King introduced the term 'permanent agriculture' in 1911, and Bill Mollison and David Holmgren coined 'permaculture' with the 1978 publication of 'Permaculture One'. It outlines three core ethics (care of the earth, care of people, and setting limits to population and consumption), Holmgren's twelve design principles, and practices such as hugelkultur, sheet mulching, and companion planting.

· Wikipedia · United States

According to the English Wikipedia article 'South Central Farm', the South Central Farm in Los Angeles operated from 1994 to 2006 as a 14-acre (5.7 ha) urban farm, considered one of the largest of its kind, used by roughly 350 families of moderate means from the surrounding community. On June 13, 2006, the Los Angeles County Sheriff's Department carried out an eviction and more than 40 protesters were arrested; on July 5, 2006, workers began bulldozing the farm amid further protests.

· Wikipedia · United Kingdom

According to the English Wikipedia article 'Manor Garden Allotments', the Manor Garden Allotments in London was a 4.5-acre (18,000 m2), 80-plot allotment site established in 1924 by Major Arthur Villiers. It was cleared in October 2007 to make way for landscaping of the London 2012 Olympic Park, and tenants were moved to a temporary site two kilometres away. Restoration on the original site and a 2.1-hectare provision of replacement plots were promised, but the successor Pudding Mill Lane allotments did not open until roughly four years after the Games ended.

· 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 · Cuba

This Wikipedia article on Cuban agriculture states the Soviets provided 63% of Cuba's food imports and 90% of its petroleum before 1990; after the collapse, agricultural production fell 54% between 1989 and 1994. By 2002, 35,000 acres (140 km2) of urban gardens produced 3.4 million metric tons of food, 90% of Havana's fresh produce came from local urban farms, and by 2003 more than 200,000 Cubans worked in the expanding urban agriculture sector. More recently, cooperatives and family farmers manage about 69% of Cuba's agricultural land.