Energy usage in Europe's biggest economy had already fallen to its lowest level since the early 1970s in 2019 due to its long-term shift to service industries and greater efficiency.
Primary energy refers to raw energy sources such as fossil fuels and renewables not converted into other forms.
Germany used 398.8 million tonnes of coal equivalent, an industry standard measure, in 2020, compared with 436.8 million tonnes a year earlier, AGEB data showed.
Much of the overall reduction came from lower coal use in power generation and steelmaking and as more brown coal plants moved into reserve status, contributing to a sharp decline in carbon emissions, AGEB said.
At the same time, renewable power plants raised output, due to favourable weather and ongoing capacity expansion.
Overall, German carbon emissions fell by around 80 million tonnes, representing a 12% drop, AGEB said.
Use of mineral oil products in road transport and aviation contracted last year.
But lower prices of heating oil encouraged private consumers to replenish their home storage tanks.
(Reporting by Vera Eckert, editing by David Evans)
