In most applications, initial investments are required to implement energy conservation measures. ˜ese initial costs must be generally justi‘ed in terms of a reduction in the operating costs (due to energy cost savings). ˜erefore, most improvements in the e—- ciency of energy systems have a delayed reward; that is, expenses come at the beginning of a retro‘t project, while the bene‘ts are incurred later. For an energy retro‘t project to be economically worthwhile, the initial expenses have to be lower than the sum of savings obtained by the reduction in the operating costs over the lifetime of the project.