ITU‐T's Technical Reports and Specifications 805 6.2.1 Environmental sustainability This clause lists the core indicators defined for environmental sustainability. There are 10 indicators in this dimension, covering air pollution, GHG emissions, renewable energy, energy saving in households, environment perception, quality of water resources, recycling of waste, noise and soil pollution, and green areas etc. Sub‐dimension Indicator Description D2.1 Air quality I2.1.2 Air pollution intensity Level of particles and toxic substances. (*) NOTE – This includes toxic substances and particles such as PM10 and PM2.5. D2.2 CO2 emissions (**) I2.2.1 GHG emissions Amount of GHG emissions per capita. (*) NOTE – It is preferred to distinguish between emissions emerging from industrial (manufacturing, construction), commercial, household, transport, and waste disposal, etc. D2.3 Energy I2.3.1 Use of alternative and renewable energy Proportion of renewable energy consumed in the city. (*) NOTE – Renewable energy sources include geothermal, solar thermal, solar voltaic, hydro, wind, and combustible renewable sources and waste (composed of solid biomass, liquid biomass, bio‐gas, industrial waste and municipal waste). I2.3.2 Energy saving in households Energy saving in households compared to a baseline. (*) NOTE – The baseline may be either a previous measurement or a reference value. NOTE – It would be preferred to distinguish between households with and without smart meters, and with and without home automation systems. D2.5 Water, soil and noise I2.5.3 Quality of city water resources Quality of water resources (rivers, lakes etc.). (*) NOTE – Pollution of water resources includes (but is not limited to) acidity, organic, floatables, alga, chemical substances and bacteria, etc. I2.5.4 Recycling of waste Proportion of waste recycled compared to total collected waste. (*) I2.5.5 Exposure to noise Proportion of the city inhabitants with noise levels above international/national exposure limits at home. (*) NOTE – Noise is measured as sound pressure in accordance with relevant international/national standards.