Energy efficiency measures often constitute very profitable investments. However, they are only slowly implemented. One of the main obstacles is the great effort the identification of potential savings in companies involves. Especially small and medium-sized enterprises (SMEs) find it difficult to uncover energy deficiencies in systems and buildings. In order to assess whether plants or entire organisations are energy -efficient, benchmark values are needed. Companies have to carry out mutual comparisons i n order to evaluate whether their economic activities are comparatively energy-efficient or not. Energy efficiency benchmark-ing provides a way to assess the energy efficiency by comparing the specific energy demand of comparable processes as well as entire production processes. The study “Energy Efficiency Benchmarking: Methodological foundations for the develo p-ment of energy efficiency benchmarking systems pursuant to EN 16231” intends to establish a methodological framework for the creation of online-based energy efficiency benchmarking systems and thereby especially illustrate the key challenges. The summary report summa-rises the results of the study.