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What are the Best Indicators for Measuring the Sustainability of Cities?

 Environmental targetsAll over the world, individuals, groups, towns and cities are struggling with the knowledge that in total, humanity's activities breach the ability of the planet to support them. There is a wide variety of initiatives and programs which are being developed to try to address this and in my last post I asked if we could define a universal standard for the environmental aspects of sustainable towns and cities.

This post builds upon some responses I have received to that post.

I have just begun a project to encourage towns in Wales and hopefully later the UK to declare themselves as One Planet Towns in the same way that Bioregional is encouraging cities like Brighton and Bristol to become one planet cities. We in the One Planet Council believe that One Planet Town status is what transition towns might be or could be transitioning to.

The advantage of this is that there can be measurement, goals and verification. The advantage of having an objective and universal standard is that it enables comparisons to be made. One can compare one town's performance against another, just as one can compare the energy performance of a building or the health of its occupants against that of another building.

These comparisons need to be made against baselines, which should be established for each town at the beginning, but while it is useful to deal with percentage reductions or increases of particular indicators against those baselines, these are not absolute measurements. Absolute measures enable one area to be compared with another.

Carbon accounting is a form of absolute measurement. It is now relatively easy to both state the annual carbon emissions of a country or a city (absolute) and the percentage improvement on previous years (relative). A measurement of the overall sustainability of a town or city would incorporate this indicator amongst others.

The European Union's sustainable towns and cities program built around the Aalborg process is predicated upon monitoring. It uses:

  • The Integrated Urban Monitoring in Europe (IUME) initiative by the European Environment Agency (EEA) – which hasn't been updated for four years; and
  • The Reference Framework for Sustainable Cities (RFSC), a still-active online toolkit for European local authorities working towards an integrated management approach. It includes a broad collection of indicators in order for cities to compile their individual set.

This uses 28 indicators of which five are environmental:

15 Greenhouse gas emissions – in tons per capita
16 Share of renewable in energy consumption
17 (Percentage of) Areas designated for nature protection and biodiversity under either municipal, communal, national or local schemes
18 The number of times that the limit PM10 permitted by the European directives on air quality is exceeded
19 Soil sealing (m2) per capita.

These are all absolute indicators, enabling proper comparisons to be made between cities of different sizes.

ISO 37120

Objective indicators are also the intention behind ISO 37120 Sustainable Development of Communities: Indicators for City Services and Quality of Life. It includes 46 indicators covered under these headings:

  • Economy
  • Education
  • Energy
  • Environment
  • Finance
  • Fire and emergency response
  • Governance
  • Health
  • Recreation
  • Safety
  • Shelter
  • Solid waste
  • Telecommunications and innovation
  • Transportation
  • Urban planning
  • Wastewater
  • Water and sanitation.

Of the 46 indicators, these are explicitly about environmental matters:

  1. Total residential electrical use per capita (kWh/year)
  2. Energy consumption of public buildings per year (kWh/m2)
  3. Percentage of total energy derived from renewable sources, as a share of the city's total energy consumption
  4. Fine particulate matter (PM2.5) concentration
  5. Particulate matter (PM10) concentration
  6. Greenhouse gas emissions measured in tonnes per capita
  7. Percentage of city population with regular solid waste collection (residential)
  8. Total collected municipal solid waste per capita
  9. Percentage of city's solid waste that is recycled
  10. Percentage of city population served by wastewater collection
  11. Percentage of the city's wastewater that has received no treatment
  12. Percentage of the city's wastewater receiving primary treatment
  13. Percentage of the city's wastewater receiving secondary treatment
  14. Percentage of the city's wastewater receiving tertiary treatment
  15. Percentage of city population with potable water supply service
  16. Percentage of city population with sustainable access to an improved water source
  17. Percentage of population with access to improved sanitation
  18. Total domestic water consumption per capita (litres/day).

Few of these are absolute measures that relate to planetary limits, the point of the ecological footprint method. Only numbers 6 and 8 are: greenhouse gas emissions measured in tonnes per capita and collected municipal solid waste per capita. 18 is also an absolute measure but not related to ecological footprinting since the amount of water available to a population for consumption will vary by location; what is perhaps interesting from an environmental sustainability angle is the water's life-cycle impact or energy intensity.

It is claimed that ISO 37120:2014 can be used by any city, municipality or local government wishing to measure its performance in a comparable and verifiable manner, irrespective of size and location or level of development. It is being developed as part of an integrated suite of standards for sustainable development in communities by the Global City Indicators Facility, a program of the Global Cities Institute.

It is early days for the standard since it was only published in May 2014 following a development period using input from international organizations, corporate partners, and international experts from over 20 countries. Nine pilot cities, including Bogotá, Toronto, São Paulo and Belo Horizonte originally helped to devise a list of some 115 initial indicators; eventually there were 258 participating cities across 82 countries.

ISO 31720 is meant to provide a comprehensive set of indicators and a methodology that will enable any sized city in a developed or a developing economy to measure its social, economic, and environmental performance in relation to other cities. The standard includes 54 other supporting indicators.

New additional indicators on sustainable development and resilience are currently being developed within the ISO, led by the GCIF. As of December 2014 the standard is being piloted by just one city: Mexico City.

Ecological footprinting

I also mentioned ecological footprinting in my last post, because this seems to be fundamental, and I compared it to life-cycle analysis. In response to this, Mathis Wackernagel, president of the Global Footprint Network (GFN), got in touch to say that the GFN is "trying to make the Footprint more relevant to cities" and welcoming any suggestions.

He said that far from being professional or commercial secrets, the method and calculations behind the footprinting method which they use are publicly available. For example here:

"And we make the templates available for free to academics. (we only charge for commercial use)," he says. "The underlying concept is quite simple: add up all demands on nature that compete for space".

"Life cycle assessment is not a competitor of Footprint.," he continued, "Footprint is an aggregator, an interpretation lens. To calculate the Ecological Footprint of a product, you need a life cycle assessment first. With those LCA data points then you can calculate Footprint."

It is also worth pointing out, of course, that the Footprint is a measure of 'unsustainability', not a measure of sustainability.

I have also heard from the British Standard Institue's John Delaney who has alerted me to this and to more issue-specific standards like PAS 2070 for city GHG footprint; process standards like BS 8904 (referred to in the prrevious post), a management system ISO that is in development; or some combination of both, like the European Reference Framework above.

He writes:

"What option cities choose depends on what suits them and/or what they are most comfortable with. Process standards can be more powerful, and help develop strategy, vision, objectives and targets, but they take commitment and resources. Reporting standards give a quick indication of how your city is doing against a raft of issues that are commonly agreed to be important, and they allow ranking of city performance.

"There is also a split between [new] development standards [systems] like One Planet Development, BREEAM Communities, etc. and standards for sustainable development of existing communities and cities. 

"We have talked for some time about developing a general footprinting standard, but it has never gained enough momentum/interest to get going. I'd be very happy to have a chat about how you could get involved in standards development and/or how we could re-boot the footprinting idea. Maybe cities and communities would be a good sector to focus on first."

Anyone who would you like to be involved in this process is welcome to contact me.

David Thorpe is the author of: