[en] Despite progress that has been made in recent years, further improvements are needed in the methodologies commonly used to evaluate the energy savings arising from voluntary energy-efficiency programs. These voluntary programs are characterized by the fact that they do not involve mandatory codes or standards but instead use information and incentives to further the adoption of energy-efficient technologies and practices. Voluntary programs frequently are aimed at long-term transformation of markets that make lasting changes in consumer patterns of energy use. To date, many of the evaluations of such programs have focused on the direct effects to program participants and have not addressed the associated market transformation to the extent possible. Using information gathered through an extensive methodological review, the authors describe useful approaches taken in previous evaluations and draw conclusions concerning the best methods available for forecasting and measuring the impacts of voluntary programs