Taipei's New Building Greening Rules require a 40-70% Green Plot Ratio on new construction, feeding Taiwan's island-wide EEWH certification system (12,585 buildings certified by 2024). Peer-reviewed hydrology finds seasonal stormwater cuts of 14-59%, weakest in heavy storms.
40-70 %
Green Plot Ratio requirement (current rule)
12,585 buildings/projects
Buildings certified or candidates, nationally (as of January 2024)
304.5 hectares (of 26,855 ha total city area)
Structurally convertible grey roof area (2022 study)
up to 59 %
Stormwater runoff reduction, cold season (2022 study)
14-28 %
Stormwater runoff reduction, rainy season (2022 study)
4-6 degrees C
Air-temperature reduction near green roofs (local thermal studies)
Details
Maturity
Established
Promoter
Taipei City Government; Taiwan Architecture & Building Center (EEWH green building certification)
Period
1999-present
Keywords
urban planning, building regulation, green infrastructure, stormwater management
Context
Taipei City's New Building Greening Implementation Rules require new construction projects to reach a Green Plot Ratio (GnPR) of 40-70%, with public buildings and schools held to the upper end of that range. The rule sits within Taiwan's wider EEWH green-building certification system, established in September 1999 as the world's second national green-building rating system after the United States' LEED.
Results
As of January 2024, 12,585 buildings or projects across Taiwan had been certified or were candidates for certification as green buildings, with certified buildings projected to cut lifetime electricity use by roughly 20% and water use by roughly 30% over a 40-year building life. A 2022 peer-reviewed hydrological study modelling the conversion of Taipei's grey roofs to green roofs found that, of the city's 26,855-hectare total area, only 304.5 hectares of grey roof were structurally suited to conversion. Where converted, green roofs cut stormwater runoff by up to 59% in the cold season, but only 14-28% during the rainy season, since substrate saturation limits performance in high-intensity storms.
Conclusions
Separate local studies on green-roof thermal effects found air-temperature reductions of roughly 4-6C near vegetated roofs. Researchers note that thermal performance is the best-studied outcome locally, while stormwater and biodiversity effects remain comparatively under-monitored citywide despite the mandate's scale.
Implementation
Indicative cost
Low (< €50k) — No public total cost figure for the mandate itself; compliance costs are borne per-project by developers, offset by projected lifetime savings of roughly 20% electricity and 30% water use.
Time to results
Long (> 3 years) — In force since 1999 as part of Taiwan's EEWH system, with over two decades of accumulated certification data.
Staffing & skills
Taipei City Government, regulator, Taiwan Architecture & Building Center, EEWH certification body
Conditions for success
Binding municipal ordinance (40-70% Green Plot Ratio) nested in a mature national EEWH certification system running since 1999
Higher requirement (upper end of range) for public buildings and schools, letting government lead by example
A quarter-century track record providing a large certified-building dataset
Common failure modes
Only about 1% of the city's total roof area is structurally suited to green-roof conversion
Stormwater performance drops sharply in heavy, high-intensity storms due to substrate saturation
Biodiversity effects remain comparatively under-monitored despite the mandate's scale
Where it fits
Governance type
binding municipal ordinance nested in a national certification system
Scale
city-wide (Taipei), nested in a national system
Income level
high-income (Taiwan)
Do you run this practice?
Claim it —
verified implementers get a public contact pathway and can propose corrections.
Data sources
Where this practice's information was retrieved from, and when.
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