Research & reports

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.

· 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.

Sota Takagi, Miki Saijo, T. Ohashi · International Journal of Gastronomy and Food Science · Japan

This study identified potential Community-Supported Agriculture (CSA) participants in Japan and validated existing theories on CSA participation through a quantitative analysis of 2484 Japanese consumers using choice experiments and Latent Class Analysis. Five distinct consumer segments were identified, with "Food Education and Learning Opportunities" and "Contribution to Environmental and Social Issues" being key drivers for participation across all segments. Factors related to "Variety of Ingredients" were less influential.

Nakata Taichi, Naoyuki Nakahama, Nobuko Ohmido, Atushi Ushimaru · Journal of Ecology · Japan (Kyoto-Osaka-Kobe)

This study investigated the effects of urban habitat diversity on plant trait diversification in the Kyoto-Osaka-Kobe megacity, Japan, using a common garden experiment with seeds from 23 Commelina communis populations from rural agricultural lands, urban agricultural lands, parks, and roadsides. Urban habitats generally exhibited higher soil pH and land surface temperature. Urban populations, particularly those from roadsides, showed distinct traits such as increased plant height, larger plant height/width ratio, fewer shoots and leaves, and/or larger leaves compared to rural populations. QST-FST comparisons and trait-environment relationships strongly suggest that local adaptation to hot, shaded, and/or eutrophic urban environments drove the observed trait divergence among various urban populations.

V J Valli Sri · International Journal for Research in Applied Science and Engineering Technology · Japan

A paper proposes a soilless rooftop urban farming model for Japan, a space-constrained country, using climate-resilient Ragi (finger millet) and Pearl Millet grown in grow bags, combined with rainwater harvesting, QR-code traceability, and biofortified microgreens. The model incorporates recent epigenetic findings linking environmental stress to heritable gene expression to improve stress tolerance without genetic modification, and is described as youth-friendly, scalable, and aligned with organic farming principles.

東京都環境局 · 東京都環境局 · Japan

Tokyo's Green Plan System, based on the Tokyo Ordinance on Protection and Recovery of Natural Environment, requires development and building projects on sites of 1,000 sqm or more (250 sqm or more for national/local government sites) to meet a minimum greening standard. It cites heat island mitigation, air purification, and rainwater infiltration as goals, and publishes wall-greening guidelines and rooftop greening performance data.

東京都 · 東京都例規集 · Japan

Article 14 of the Tokyo ordinance requires developers building or renovating on sites of 1,000 sqm or more (250 sqm or more for national/local government sites) to submit a greening plan covering both ground-level and building-top (e.g. rooftop) greening to the governor before starting work, to report completion of the greening afterward, and to properly maintain the resulting green space. Enacted December 22, 2000, with the most recent amendment taking effect June 1, 2025.

国土交通省 · 国土交通省 · Japan

According to this December 12, 2025 announcement by Japan's Ministry of Land, Infrastructure, Transport and Tourism, approximately 14.5 hectares of green roofs (equivalent to about two National Stadiums) and 4.6 hectares of green walls were newly installed nationwide in FY2024. Cumulative installations from FY2000 through FY2024 (25 years) reached about 633 hectares of green roofs and 131 hectares of green walls.

東京都環境局 · 東京都環境局 · Japan

This Tokyo Metropolitan Government Bureau of Environment page describes the Green Space Plan Notification System, which requires developers building or expanding structures on sites of 1,000 m2 or more (250 m2 or more for national/local government sites) to file a green space plan and meet a minimum greening standard, under the ordinance on nature protection and restoration in Tokyo. The system aims to restore lost green space and mitigate the urban heat island effect, requiring prior consultation and post-completion reporting.

東京都環境局 · 東京都環境局 · Japan

This Tokyo Metropolitan Government Bureau of Environment page compiles and publishes rooftop, wall, and balcony greening results based on green space plan filings from FY2000 through FY2024. The page text itself does not state cumulative totals; detailed figures are provided separately in downloadable Excel and PDF result tables.

Ahmya Ayaka, Fujita Hanako, Hide Haruka · Techno Agriculturae Studium of Research · Japan

This study explored the impact of verticulture technology on urban agriculture in Japan using a mixed-methods approach, including field experiments, farmer surveys, and production record analysis. The findings indicated that verticulture technology significantly improved crop yields by up to 30% per square meter and reduced water usage by 50% compared to traditional urban farming. It also lowered greenhouse gas emissions and minimized land use, demonstrating its potential for enhancing food production efficiency and sustainability in urban settings.

東京都 · 東京都例規集 · Japan

Article 6 of the enforcement rules for the Tokyo nature protection ordinance sets the detailed greening standards: ground-level greening must cover 0.2-0.35 times (site area minus building footprint), depending on site size (Appended Table 2); building-top (rooftop) greening must cover 0.2-0.35 times the rooftop area (Appended Table 4); street-facing greening ratios range from 3/10 to 8/10 (Appended Table 3); and planting density is set at 1 tall tree, 2 medium trees, and 3 shrubs per 10 sqm. Enacted in 2001, most recently amended in March 2024.

国土交通省 · 国土交通省 · Japan

MLIT's national survey of rooftop and wall greening construction results for FY2023 found about 15.7 hectares of new rooftop greening (roughly three Tokyo Domes) and 5.0 hectares of new wall greening that year, bringing the cumulative totals since FY2000 to about 615 hectares of rooftop greening and 125 hectares of wall greening. The survey was mailed to 560 companies nationwide with 284 responses (a 50.7% response rate).

国土交通省 · 国土交通省 · Japan

According to this December 11, 2023 announcement by Japan's Ministry of Land, Infrastructure, Transport and Tourism, approximately 15.6 hectares of green roofs and 4.4 hectares of green walls were newly installed nationwide in FY2022. Cumulative installations from FY2000 through FY2022 (23 years) reached about 597 hectares of green roofs and 119 hectares of green walls (FY2021 and FY2022 figures are provisional).

横浜市港北区 · 横浜市港北区 · Japan

The rooftop garden at Kohoku Ward Office in Yokohama reopened on April 1, 2022 after waterproofing and flowerbed renovation work. It is positioned as a measure against the heat island effect, for energy savings, CO2 reduction, and environmental education, with about 20 "green supporters" active Tuesdays 10am-12pm. The ward's green coverage ratio is reported to have fallen from 33.4% in fiscal 1992 to 24.1% in fiscal 2019.

· 農林水産省（2021年5月策定） · Japan

MAFF's 2021 strategy for a sustainable food system, setting 2050 KPIs including a 50% cut in chemical pesticide use (risk-weighted), a 30% cut in chemical fertiliser use, and expanding organic farming to one million hectares — 25% of Japan's cultivated land.

農林水産省 · 農林水産省（みどりの食料システム戦略本部） · Japan

The official portal for MAFF's 'Strategy for Sustainable Food Systems, MeaDRI' (Midori Strategy), decided May 12, 2021. It aims to reconcile productivity growth with sustainability in Japan's food and agriculture sector through innovation, targeting development of key technologies by 2040 and full social implementation by 2050. Interim 2030 KPI targets were decided June 21, 2022.

Francesco Letteriello · · Japan (Nishi-Tokyo)

This research focuses on the role of urban agriculture within the UN New Urban Agenda, noting that 54% of the world's population lived in urban areas in 2015, projected to rise to 66% by 2050, leading to urban overcrowding. Nishi-Tokyo's municipality is interested in revising its Master Plan to protect "Productive Green Zones" which will lose their status in 2022. The study aims to analyze the importance of multifunctionality in urban agriculture as a driver for resilient cities, comparing urban agriculture in Italy and Japan, and deepening the context of Nishi-Tokyo through literature, interviews, and field analysis.

Kimisato Oda, Christoph Rupprecht, Kazuaki Tsuchiya, Steven R. McGreevy · Sustainability · Japan (Kyoto)

A study in Kyoto City, Japan, examined agricultural land use from 2007–2017 to assess urban agriculture as a sustainability strategy for shrinking cities. Analysis revealed a 10% decline (209 ha) in agricultural land use over ten years, with main post-agricultural uses being residential (40%) and vacant land (28%). The findings indicate that Kyoto City is not currently positioned to benefit from population decline through localized food production.

国土交通省 · 国土交通省 · Japan

MLIT's national survey of rooftop and wall greening construction results for FY2017, aimed at mitigating the urban heat island effect and lowering urban carbon emissions, recorded about 23.1 hectares of new rooftop greening (roughly five Tokyo Domes) and 5.5 hectares of new wall greening that year, bringing cumulative totals since FY2000 to about 498 hectares of rooftop greening and 90 hectares of wall greening. Average project area was 261 m2, with a growing trend toward large-scale mixed-use projects.

肇 石原, Hajime Ishihara · Institutional Repositories DataBase (IRDB) · Japan (Osaka)

This study analyzed changes in green space components (parks, agricultural land, forests) across Osaka Prefecture, Japan, from 1970 to 2010. While forest area decreased slightly and park area increased, the increase in park area was insufficient to offset the significant reduction in agricultural land. Consequently, the overall green space ratio in Osaka Prefecture showed a declining trend, particularly noticeable in Osaka City and its surrounding areas.

国立環境研究所 · 国立環境研究所 環境展望台 · Japan

This National Institute for Environmental Studies explainer on rooftop and wall greening (revised May 2016) cites a 1985 Chubu Electric Power experiment finding 20-30% energy savings compared to traditional sunshades (yoshizu). It reports about 413.8 hectares of rooftop greening and 68.0 hectares of wall greening installed nationwide over the 15 years from FY2000 to FY2014, with FY2014 alone contributing about 26.9 hectares of rooftop and 5.0 hectares of wall greening, though FY2009 saw about a 20% year-on-year contraction. It also notes implementation challenges such as structural load assessment, root-barrier installation, and ongoing irrigation management.

Takanori Kuronuma, Saori Hashimoto, Ryuta CHIMURA, Haruaki YOKOKAWA, Kazunori Sakamoto, Hitoshi Watanabe · Journal of the Japanese Society of Revegetation Technology · Japan

This study investigated the annual changes in lightweight soil in a thin substratum rooftop garden planted with Zoysia grass. No annual changes were observed in grass growth or soil physical properties. Soil organic matter tended to increase after construction, and nutrient salt content was comparable to golf course green soil diagnostic standards. However, nutrient salt levels in unused lightweight soil were significantly higher than after construction and decreased annually. No difference in nutrient salt content was confirmed with or without additional fertilization, suggesting the need for fertilization management tailored to the unique rooftop environment.

Yugo YAMAMOTO, Asami ORITA, Motoyuki NAGAI · Studies in Regional Science · Japan (Osaka)

A questionnaire survey was conducted among LOHAS (Lifestyles of Health and Sustainability) and general consumers in Osaka Prefecture to identify sustainable lifestyles related to food production and consumption and evaluate their effect on CO2 emissions. LOHAS consumers tended to participate in local food production activities and make purchasing decisions based on health and environmental consciousness. Their total daily life CO2 emissions were 15% lower than regular consumers, but their transportation-related CO2 emissions were higher due to roundtrips to local farm shops.