Daylight saving time uses more energy, not less

Matthew J. Kotchen, a professor of environmental economics at the University of California in Santa Barbara, and Laura E. Grant, a doctoral student in the same field, studied the effects of daylight saving in Indiana, where some counties used it and others did not. The states changed the law two years ago so that all counties now use daylight saving time.

In an interview, Kotchen said using residential electricity bills for Indiana, he and Grant found that daylight saving time reduced electricity use for lighting but that more was used for air conditioning in the summer and heating in the fall than was saved.
USA Today