The U.S. Environmental Protection Agency’s Clean Power Plan offers regulators a wide spectrum of policy and technology options for compliance. In addition to the four main building blocks that are used to determine individual state emissions reduction targets – heat rate improvements, re-dispatch to natural gas, energy efficiency, and non-emitting generation like renewable energy and nuclear power – states may choose “outside the fence” options when drafting an approvable compliance plan. At a meeting of the National Association of State Energy Officials (NASEO), Ken Colburn recommended that states consider one of the lowest-cost options — privately-delivered energy efficiency.Non-ratepayer energy efficiency reduces power sector emissions and, with a low cost and numerous co-benefits, is even easier to implement than utility-sponsored demand-side management. The cheapest kilowatt hour is the kilowatt hour saved, but this is not necessarily the easiest path to compliance. The key is quantifying the avoided emissions from energy efficiency policies and programs. Mr. Colburn outlines various options for quantifying avoided emissions as part of potential studies and evaluation, measurement, and verification programs. Existing methods, such as deemed energy savings, the “AP-42 emission factors” approach, and the MOVES model for assessing vehicle emissions, can all be adapted to be used to quantify avoided emissions due to energy efficiency.