US energy-related carbon dioxide (CO2) emissions totalled 2.53 billion metric tons in the first six months of 2016, the US Energy Information Administration reports. This is the lowest emissions level for the first six months of any year in 25 years.

Mild weather and changes in the fuels used to generate electricity contributed to the decline in energy-related emissions, according to EIA. The organisation projects energy-associated CO2 emissions will fall to 5.18 billion metric tons in 2016, the lowest annual level since 1992.

In the first six months of 2016, the U.S. had the fewest heating degree days (a heating demand indicator) since at least 1949, Kallanish Steel’s sister publication Kallanish Energy reports.

Overall, total primary energy consumption was -2% lower compared with the first six months of 2015. The decrease was most notable in the residential and electric power sectors, where primary energy consumption decreased -9% and -3%, respectively.

Coal and natural gas consumption each fell compared to the first six months of 2015, EIA found. The decrease was greater for coal, which fell -18%, while natural gas consumption fell -1%.

Renewable fuels consumption increased 9% during the first six months of 2016 compared with the same period in 2015. Wind energy, which saw the largest power generating capacity additions of any fuel last year, accounted for nearly half the increase.

Hydroelectric power, which has increased with the easing of drought conditions on the West Coast, accounted for 35% of the increase in consumption of renewable energy. Solar energy accounted for 13% of the increase and is expected to see the largest capacity additions of any fuel in 2016.