China's energy intensity, the amount of energy consumed per unit of GDP, has been decreasing at an accelerating pace in the past few years, official data showed on Friday.

In 2015, China's energy intensity declined 5.6 percent from the previous year, following the 4.8-percent and 3.7-percent falls seen in 2014 and 2013, according to the National Bureau of Statistics (NBS).

Coal consumption accounted for 64 percent of the primary energy use last year, down 4.5 percentage points from the share in 2012, as the government pushes for cleaner and greener growth despite the slowing economy.

"The data showed China's energy structure is becoming more diversified and optimized," said the NBS.

China has specified that it aims to bring the share of non-fossil energy to 15 percent by 2020 and 20 percent by 2030. In addition, coal consumption will be limited to 62 percent of energy use by 2020.

The government has pledged that it will strictly control new capacity in the coal industry and that it won't approve any new coal mines before 2019.