Sound evaluation needs sound numbers. But measuring energy savings is measuring something that is not used and can meet unexpected difficulties. The European Commission has made strong efforts to harmonize methods to measure energy efficiency and energy savings and to monitor the progress towards the goals of the Energy Efficiency Directive. However, in practice, multiple methods are still used, which may lead to confusion. In this paper, we use the Netherlands as a case study to analyze this phenomenon. In the Netherlands, three national indicators on energy efficiency exist, next to a European indicator next to the impact of individual policy instruments. The large differences and sometimes contradictory results of the different indicators lead to questions about what is the “best” method. This paper studies the reasons behind the differences between the methods used for industrial energy efficiency improvement in the Netherlands. It compares detailed bottom-up data from individual policy instruments with top-down national figures. We disentangle the impact of volume, efficiency, and structure effects. In this way, we visualize the differences between several methods and the impact of the choice of metrics used in those methods. This helps understanding why care should be taken when comparing industrial energy efficiency results from different countries.