The researchers looked at how energy consumption changed in different parts of China from 1995 to 2015. They broke down why energy use went up or down in each place. They found that economic growth made energy use go up, but improvements in energy efficiency helped bring it down. The eastern part of China had less of a role in increasing energy use compared to the western side. The western region became the biggest energy user in the country between 2010 and 2015. Energy efficiency got much better in China overall, mostly because each region used energy more efficiently. Different areas of China need different energy policies instead of one policy for the whole country.