The Green City Index methodology was developed by the Economist Intelligence
Unit (EIU) in cooperation with Siemens. Cities were selected for
their size and importance (mainly capital cities and large population or
business centres). They were picked independently, rather than relying
on requests from city governments to be included or excluded, in order
to enhance each Index’s credibility and comparability.
The Green City Index series measures cities on approximately 30 indicators
across eight to nine categories depending on the region. It covers
CO2 emissions, energy, buildings, land use, transport, water and
sanitation, waste management, air quality and environmental governance.
About half of the indicators in each Index are quantitative – usually
data from official public sources, for example, CO2 emissions per
capita, water consumption per capita, recycling rates and air pollutant
concentrations. The remainder are qualitative assessments of the city’s
environmental policies – for example, the city's commitment to sourcing
more renewable energy, traffic-congestion-reduction policies and air
quality codes. Measuring quantitative and qualitative indicators together
means the Indexes are based on current environmental performance as
well as the city‘s intentions to become greener.
The specific indicators differ slightly from Index to Index, taking into
account data availability and the unique challenges in each region. For
example, the African Index includes indicators measuring access to electricity
and potable water, and the percentage of people living in informal
settlements.
Each city receives an overall Index ranking and a separate ranking for
each individual category. The results are presented numerically (for the European,
and the US and Canada Indexes) or in five performance bands from
“well above average” to “well below average” (for the Asian, Latin Ameri can
and African Indexes). Bandings are used in regions where levels of data
quality and comparability do not allow for a detailed numerical ranking.