the commercial sector consists of retail stores, offices (business and government), restaurants, schools and other workplaces. energy in this sector has the same basic end uses as the residential sector, in slightly different proportions. space conditioning is again the single biggest consumption area, but it represents only about 30% of the energy use of commercial buildings. lighting, at 25%, plays a much larger role than it does in the residential sector. lighting is also generally the most wasteful component of commercial use. a number of case studies indicate that more efficient lighting and elimination of over-illumination can reduce lighting energy by approximately fifty percent in many commercial buildings.