Figure 3.13c-d: Relative
levels of energy efficiency for selected industrial sectors in various countries.
The aggregate energy efficiency index (EEI) is calculated as: EEI = (S_{i}
P_{i} ·SEC_{i})/( S_{i} P_{i} ·
SEC_{i,BP}), where P_{i} is the production volume of product i;
SEC_{i} is the specific energy consumption for product i, and SEC_{i,BP}
is a best-practice reference level for the specific energy consumption for product
i. By applying this approach a correction is made in order to account for structural
differences between countries in each of the tracked industrial sectors. A typical
statistical uncertainty for these figures is 5%. Because of statistical errors
higher uncertainties may occur in individual cases.