The requirements or guidelines presented in this document, a NEMA Lighting Systems Division white paper, are considered technically sound at the time they are approved for publication. They are not a substitute for a product sellers or users own judgment with respect to the particular product discussed, and NEMA does not undertake to guarantee the performance of any individual manufacturers products by virtue of this document or guide. Thus, NEMA expressly disclaims any responsibility for damages arising from the use, application, or reliance by others on the information contained in these white papers, standards, or guidelines. The opinions expressed in this statement represent the consensus views of the member companies of the Lighting Systems Division of the National Electrical Manufacturers Association. To justify their investments, utilities must have a way to capture the certain savings associated with incentive programs for lighting systems. Energy efficiency programs offer rebates and other financial incentives in return for residential and commercial building owners installing energy-efficient lighting systems. For this whitepaper, we define a lighting system as a combination of controls, sensors, lamps and/or luminaires. When used effectively, these incentives offset the building owners capital cost to install products and systems, which greatly reduce a buildings total energy consumption. Here E(t2,t1) is the energy consumed between time t1 and t2, and P(t) is the instantaneous power consumed at every instant of time between t1 and t2. For lighting systems in buildings, the power consumed at any instant in time is less than or equal to the maximum power the lighting system could draw (for example, when all the lights are on at their brightest setting).