Consumer comparison and switching service Uswitch has conducted a study that has found that Canberra is the most sustainable city in the world.

The study scores a city out of 600 for its sustainability measures based on energy, transportation infrastructure, affordability, pollution, air quality, Co2 emissions and the overall percentage of green space available within the city.

The nation's capital scored a total of 427, thanks to it’s excellent public transport service, renewable and sustainable energy sources, and recording one of the lowest scores at 13.89 on Uswitch’s pollution index. Canberra relies heavily on solar power and nearby wind farms, with 94% of residents connected to high speed internet also a contributor to its high score. 

Spanish capital Madrid came in second with a score of 403, with Brisbane taking third place. The river city scores low on pollution rates at 21.8 percent and a high transport infrastructure percentage at 75 percent. Two Australian cities in the top three highlights the commitment to sustainability Australian cities hold, with the use of solar power a major reason for both cities’ high scores.

Wellington, New Zealand has less pollution than anywhere else, scoring 13.66 on the pollution index, meaning out of every 100 particles of air, only 13.66 are polluted. Nairobi, Kenya scored highest for renewable energy, with 90% of its energy sources sustainable, with the bulk of it coming from hydroelectricity or geothermal energy. 

At the other end of the spectrum, Saudi Arabian port city Jeddah scored the lowest on the Uswitch index, making it the least sustainable city in the world according to the study. With a heavy reliance on fuel and gas, the city reflects much of Saudi Arabia, with the national economy funded by fossil fuel exports, which increase the country’s bank balance but badly damage its impact on the environment. New Delhi, India was ranked as the second least sustainable city, with Amman in Jordan scoring third lowest.

To read the full study carried out by Uswitch, click here.