The European Green City Index measures the current environmental performance of major European cities, as well as their commitment to reducing their future environmental impact by way of ongoing initiatives and objectives. The methodology was developed by the Economist Intelligence Unit in cooperation with Siemens. An independent panel of urban sustainability experts provided important insights and feedback on the methodology. The Index scores cities across eight categories — CO2 emissions, energy, buildings, transport, water, waste and land use, air quality and environmental governance — and 30 individual indicators. Sixteen of the index’s 30 indicators are derived from quantitative data and aim to measure how a city is currently performing — for example, its level of CO2 emissions, the amount of energy it consumes, how much waste it produces or levels of air pollution. The remaining 14 indicators are qualitative assessments of cities’ aspirations or ambitions — for example, their commitment to consuming more renewable energy, to improving the energy efficiency of buildings, to reducing congestion or to recycling and reusing waste.