The industrial sector led the way to smaller power demand with a reduction of 5.3 percent last year compared with 2014.
Only one among 13 industrial sectors saw an increase on demand, mineral extraction.
Metallurgy cut electricity demand the most, by 12.5 percent, reflecting downturns in auto production and construction.
According to the EPE report, Brazilian households reduced power use in 2015 by the first time since 2002, when Brazil was in the middle of a electricity rationing.
Brazilian houses used 0,6 percent less energy than in 2014, even as 1.6 million new residences were connected to the grid for the first time.
EPE said the fall reflected the higher prices for electricity - up to 60 percent higher in some states - after two years of drought forced the use of more expensive, thermal generation.