How can sustainability be measured?
Measuring sustainability is a key aspect for any decision maker, and achieving targets and monitoring of policies depends on indicators. Single and combined or multiple indicators may be used. The largest organisation globally involved with assessing sustainability indicators is the United Nations.
The UN definition of a sustainable city is as follows:
A sustainable city […] is a city where achievements in social, economic, and physical development are made to last. A sustainable city has a lasting supply of the natural resources on which its development depends (using them only at a level of sustainable yield). A sustainable city maintains a lasting security from environmental hazards which may threaten development achievements (allowing only for acceptable risk).
UN Habitat, UNHCS/UNHSP (United Nations Human Settlements Programme)
In summary, the UN suggests 23 key urban indicators and nine qualitative data subsets to assess sustainability (from the Istanbul Summit).
© United Nations
Key indicators are both important for policy and relatively easy to collect. They are either numbers, or percentages and ratios, for example on topics such as water consumption, air pollution, wastewater treated or crime rates.
Qualitative data or checklists give an assessment of areas which cannot easily be measured quantitatively. For example community involvement in planning can be quantified and is. Often known as 'bottom-up' involvement, it comprises local people participating in decisions about their environment. This will be particularly important in cities with diverse or marginal ethnic and cultural groups.
Problems in data collection
Data is dynamic and often difficult to collect – not to mention an expensive process! Here are some of the main problems with data collection to measure sustainability. Overcoming these problems is vital for any city planner:
- lack of city-based data, may only be available nationally
- lack of contemporaneous data, meaning it may not all have been gathered at the same time/date
- large number of organisations holding the data – some of whom may be biased towards certain types of data
- different indicators selected by city authorities
- inaccuracies in data collection
- rapid change in statistics as cities evolve
- cost in gathering data – which will penalise cities in LEDCs (Less Economically Developed Countries)
UN agencies define indicators and modes of data collection to assess sustainability.