The electrical consumption in most commercial facilities can easily account for 50 to 75% of the total utility costs. A thorough knowledge of how electricity is used in a facility can be invaluable to the electrical system audit. The evaluation should include an electric demand profile for the building. The measurements may have to be taken both in the cooling and heating season. Most electric utilities either have this data available for their customers or can provide this service at a nominal charge. Lighting accounts for a significant portion of electrical energy consumed in a building. Energy is saved in the lighting system by reducing illumination levels, improving lighting system efficiency, curtailing operating hours, and by taking advantage of available daylighting. Incandescent lamps have the lowest lamp efficacies of the commonly used lamps. General service incandescent lamps do not have good lumen maintenance throughout their lifetime.