; and (B) the increase in CHP system savings from upgrading or replacing, after the date of enactment of this section, a combined heat and power system that commenced operation on or before the date of enactment of this section. (4) CHP system savings The term CHP system savings means the electric output, and the electricity saved due to the mechanical output, of a combined heat and power system, adjusted to reflect any increase in fuel consumption by that system as compared to the fuel that would have been required to produce an equivalent useful thermal energy output in a separate thermal-only system, as determined in accordance with regulations promulgated by the Secretary. (5) Combined heat and power system The term combined heat and power system means a system that uses the same energy source for the generation of electrical or mechanical power and the production of steam or another form of useful thermal energy, if— (A) the system meets all applicable requirements relating to efficiency and other operating characteristics that the Secretary promulgates by regulation; and (B) the net quantity of electricity sold wholesale by the facility using the system does not exceed 50 percent of the total quantity of electricity generated annually by the system. (6) Cost-effective The term cost-effective means, with respect to an energy efficiency measure, that the measure achieves, directly to the energy consumer and to the economy, a net present value of economic benefits over the life of the measure that is greater than the net present value of the cost of the measure over the life of the measure, using a societal benefit-cost test calculated using the lower of— (A) a utility weighted average cost of capital