EIA: “The Department of Energy (DOE) recently released a study of the 2010 lighting market, finding that lighting across all sectors became more energy efficient since their study of the 2001 lighting market. The residential sector, which accounted for 25% of total lighting energy consumption in 2010, remained the least energy efficient of the sectors, primarily due to the use of incandescent lamps. Lighting efficiency is often expressed as efficacy, or the ratio of light output (measured in lumens) to the electric power input (measured in Watts). Since the DOE’s previous market characterization in 2001, the commercial sector made the most improvement in efficiency. Rather than switching between lighting types, the commercial sector switched out larger-diameter T12 linear fluorescent lamps and replaced them with smaller-diameter T8 and T5 lamps. In 2010, DOE estimated that the commercial sector accounted for half of all lighting energy consumption. The residential sector was estimated at 25%; industrial, 8%; and outdoor, 17%. Residential lighting is expected to become more efficient as new standards mandated by law go into effect.”